1.  back(n = noun.body) dorsum - the posterior part of a human (or animal) body from the neck to the end of the spine; "his back was nicely tanned"

2.  back(n = noun.artifact) rear - the side that goes last or is not normally seen; "he wrote the date on the back of the photograph"
Derived form verb back₆

3.  back(n = noun.location) rear - the part of something that is furthest from the normal viewer; "he stood at the back of the stage"; "it was hidden in the rear of the store"
Antonym: front

4.  back(n = noun.person) - (football) a person who plays in the backfield;

5.  back(n = noun.body) backbone, rachis, spinal column, spine, vertebral column - the series of vertebrae forming the axis of the skeleton and protecting the spinal cord; "the fall broke his back"

6.  back(n = noun.artifact) binding, book binding, cover - the protective covering on the front, back, and spine of a book; "the book had a leather binding"
Derived form verb back₁₀

7.  back(n = noun.artifact) - the part of a garment that covers the back of your body; "they pinned a `kick me' sign on his back"

8.  back(n = noun.artifact) backrest - a support that you can lean against while sitting; "the back of the dental chair was adjustable"

9.  back(n = noun.act) - (American football) the position of a player on a football team who is stationed behind the line of scrimmage;

1.  back(v = verb.social) endorse, indorse, plump for, plunk for, support - be behind; approve of; "He plumped for the Labor Party"; "I backed Kennedy in 1960"
Derived form noun backing₁
Sample sentences: Somebody ----s somebody; Somebody ----s something

2.  back(v = verb.motion) - travel backward; "back into the driveway"; "The car backed up and hit the tree"
Sample sentences: Somebody ----s PP; Something is ----ing PP

3.  back(v = verb.social) endorse, indorse, second - give support or one's approval to; "endorse a new project"; "I can't back this plan"; "I'll second that motion"
Derived form noun backing₁
Sample sentences: Somebody ----s something

4.  back(v = verb.motion) - cause to travel backward; "back the car into the parking spot"
Antonym: advance
Sample sentences: Somebody ----s somebody PP; Somebody ----s something PP

5.  back(v = verb.possession) - support financial backing for; "back this enterprise"
Derived form noun backer₁, noun backing₁, noun backing₃
Sample sentences: Sam and Sue %s the movie

6.  back(v = verb.stative) - be in back of; "My garage backs their yard"
Antonym: front
Derived form noun back₂
Sample sentences: Something ----s something

7.  back(v = verb.competition) bet on, gage, game, punt, stake - place a bet on; "I'm betting on the new horse"; "Which horse are you backing?"
Sample sentences: Somebody ----s on something; Somebody ----s something

8.  back(v = verb.change) - shift to a counterclockwise direction; "the wind backed"
Antonym: veer
Sample sentences: Something ----s

9.  back(v = verb.change) back up - establish as valid or genuine; "Can you back up your claims?"
Sample sentences: Somebody ----s something; Something ----s something

10.  back(v = verb.change) - strengthen by providing with a back or backing;
Derived form noun back₆, noun backing₂
Sample sentences: Somebody ----s something

1.  back(a = adj.all) - related to or located at the back; "the back entrance"; "the back yard"
Antonym: front

2.  back(s = adj.all) hind, hinder - located at or near the back of an animal; "back (or hind) legs"; "the hinder part of a carcass"

3.  back(s = adj.all) - of an earlier date; "back issues of the magazine"

1.  back(r = adv.all) - in or to or toward a former location; "she went back to her parents' house"

2.  back(r = adv.all) backward, backwards, rearward, rearwards - at or to or toward the back or rear; "he moved back"; "she looked rearward out the window of the car"; "tripped when he stepped backward"

3.  back(r = adv.all) - in or to or toward an original condition; "he went back to sleep"

4.  back(r = adv.all) backward - in or to or toward a past time; "lovers of the past looking fondly backward"; "never look back"; "set the clocks back an hour"
Antonym: ahead

5.  back(r = adv.all) - in reply; "he wrote back three days later"

6.  back(r = adv.all) - in repayment or retaliation; "he hit me and I hit him back"; "I was kept in after school for talking back to the teacher"; "we paid back everything we had borrowed"

1.  A large shallow vat; a cistern, tub, or trough, used by brewers, distillers, dyers, picklers, gluemakers, and others, for mixing or cooling wort, holding water, hot glue, etc. [1913 Webster]

2.  A ferryboat. See Bac, 1. [1913 Webster]

1.  In human beings, the hinder part of the body, extending from the neck to the end of the spine; in other animals, that part of the body which corresponds most nearly to such part of a human being; as, the back of a horse, fish, or lobster. [1913 Webster]

2.  An extended upper part, as of a mountain or ridge. [1913 Webster]

3.  The outward or upper part of a thing, as opposed to the inner or lower part; as, the back of the hand, the back of the foot, the back of a hand rail. [1913 Webster]

4.  The part opposed to the front; the hinder or rear part of a thing; as, the back of a book; the back of an army; the back of a chimney. [1913 Webster]

5.  The part opposite to, or most remote from, that which fronts the speaker or actor; or the part out of sight, or not generally seen; as, the back of an island, of a hill, or of a village. [1913 Webster]

6.  The part of a cutting tool on the opposite side from its edge; as, the back of a knife, or of a saw. [1913 Webster]

7.  A support or resource in reserve. [1913 Webster]

8.  The keel and keelson of a ship. [1913 Webster]

9.  The upper part of a lode, or the roof of a horizontal underground passage. [1913 Webster]

10.  A garment for the back; hence, clothing. [1913 Webster]

1.  Being at the back or in the rear; distant; remote; as, the back door; back settlements. [1913 Webster]

2.  Being in arrear; overdue; as, back rent. [1913 Webster]

3.  Moving or operating backward; as, back action. [1913 Webster]

1.  To get upon the back of; to mount. [1913 Webster]

2.  To place or seat upon the back. [1913 Webster]

3.  To drive or force backward; to cause to retreat or recede; as, to back oxen. [1913 Webster]

4.  To make a back for; to furnish with a back; as, to back books. [1913 Webster]

5.  To adjoin behind; to be at the back of. [1913 Webster]

6.  To write upon the back of; as, to back a letter; to indorse; as, to back a note or legal document. [1913 Webster]

7.  To support; to maintain; to second or strengthen by aid or influence; as, to back a friend. Macaulay. [1913 Webster]

8.  To bet on the success of; -- as, to back a race horse. [1913 Webster]

1.  To move or go backward; as, the horse refuses to back. [1913 Webster]

2.  To change from one quarter to another by a course opposite to that of the sun; -- used of the wind. [1913 Webster]

3.  To stand still behind another dog which has pointed; -- said of a dog. [1913 Webster]

1.  In, to, or toward, the rear; as, to stand back; to step back. [1913 Webster]

2.  To the place from which one came; to the place or person from which something is taken or derived; as, to go back for something left behind; to go back to one's native place; to put a book back after reading it. [1913 Webster]

3.  To a former state, condition, or station; as, to go back to private life; to go back to barbarism. [1913 Webster]

4.  (Of time) In times past; ago. Gladstone. [1913 Webster]

5.  Away from contact; by reverse movement. [1913 Webster]

6.  In concealment or reserve; in one's own possession; as, to keep back the truth; to keep back part of the money due to another. [1913 Webster]

7.  In a state of restraint or hindrance. [1913 Webster]

8.  In return, repayment, or requital. [1913 Webster]

9.  In withdrawal from a statement, promise, or undertaking; as, he took back the offensive words. [1913 Webster]

10.  In arrear; as, to be back in one's rent. [1913 Webster]

back, n., adv., v., & adj.
--n.
1 a the rear surface of the human body from the shoulders to the hips. b the corresponding upper surface of an animal's body. c the spine (fell and broke his back). d the keel of a ship.
2 a any surface regarded as corresponding to the human back, e.g. of the head or hand, or of a chair. b the part of a garment that covers the back.
3 a the less active or visible or important part of something functional, e.g. of a knife or a piece of paper (write it on the back). b the side or part normally away from the spectator or the direction of motion or attention, e.g. of a car, house, or room (stood at the back).
4 a a defensive player in field games. b this position.
5 (the Backs) the grounds of Cambridge colleges which back on to the River Cam.
--adv.
1 to the rear; away from what is considered to be the front (go back a bit; ran off without looking back).
2 a in or into an earlier or normal position or condition (came back late; went back home; ran back to the car; put it back on the shelf). b in return (pay back).
3 in or into the past (back in June; three years back).
4 at a distance (stand back from the road).
5 in check (hold him back).
6 (foll. by of) US behind (was back of the house).
--v.
1 tr. a help with moral or financial support. b bet on the success of (a horse etc.).
2 tr. & intr. move, or cause (a vehicle etc.) to move, backwards.
3 tr. a put or serve as a back, background, or support to. b Mus. accompany.
4 tr. lie at the back of (a beach backed by steep cliffs).
5 intr. (of the wind) move round in an anticlockwise direction.
--adj.
1 situated behind, esp. as remote or subsidiary (backstreet; back teeth).
2 of or relating to the past; not current (back pay; back issue).
3 reversed (back flow).

Idiom:
at a person's back in pursuit or support. at the back of one's mind remembered but not consciously thought of. back and forth to and fro. back bench a back-bencher's seat in the House of Commons. back-bencher a member of Parliament not holding a senior office. back-boiler Brit. a boiler behind and integral with a domestic fire. back-breaking (esp. of manual work) extremely hard. back country esp. Austral. & NZ an area away from settled districts. back-crawl = BACKSTROKE. back-cross Biol.
1 cross a hybrid with one of its parents.
2 an instance or the product of this. back door a secret or ingenious means of gaining an objective. back-door adj. (of an activity) clandestine, underhand (back-door deal). back down withdraw one's claim or point of view etc.; concede defeat in an argument etc. back-down n. an instance of backing down. back-fill refill an excavated hole with the material dug out of it.
back-formation
1 the formation of a word from its seeming derivative (e.g. laze from lazy).
2 a word formed in this way.
back number
1 an issue of a periodical earlier than the current one.
2 sl. an out-of-date person or thing. the back of beyond a very remote or inaccessible place.
back off
1 draw back, retreat.
2 abandon one's intention, stand, etc. back on to have its back adjacent to (the house backs on to a field). back out (often foll. by of) withdraw from a commitment. back passage colloq. the rectum.
back-pedal (-pedalled, -pedalling; US -pedaled, -pedaling)
1 pedal backwards on a bicycle etc.
2 reverse one's previous action or opinion. back-projection the projection of a picture from behind a translucent screen for viewing or filming. back room (often (with hyphen) attrib.) a place where secret work is done. back-scattering the scattering of radiation in a reverse direction. back seat an inferior position or status. back-seat driver a person who is eager to advise without responsibility (orig. of a passenger in a car etc.). back slang slang using words spelt backwards (e.g. yob). back-stop = LONGSTOP. back talk US = BACKCHAT. back to back with backs adjacent and opposite each other (we stood back to back). back-to-back adj. esp. Brit. (of houses) with a party wall at the rear.
back to front
1 with the back at the front and the front at the back.
2 in disorder. back-to-nature (usu. attrib.) applied to a movement or enthusiast for the reversion to a simpler way of life.
back up
1 give (esp. moral) support to.
2 Computing make a spare copy of (data, a disk, etc.).
3 (of running water) accumulate behind an obstruction.
4 reverse (a vehicle) into a desired position.
5 US form a queue of vehicles etc., esp. in congested traffic. back water reverse a boat's forward motion using oars. get (or put) a person's back up annoy or anger a person. get off a person's back stop troubling a person. go back on fail to honour (a promise or commitment). know like the back of one's hand be entirely familiar with. on one's back injured or ill in bed. on the back burner see BURNER. put one's back into approach (a task etc.) with vigour. see the back of see SEE(1).
turn one's back on
1 abandon.
2 ignore. with one's back to (or up against) the wall in a desperate situation; hard-pressed.

Derivative:
backer n. (in sense 1 of v.). backless adj.

Etymology:
OE b{aelig}c f. Gmc

VB  aid, assist, help, succor, lend one's aid, come to the aid, of, contribute, subscribe to, bring aid, give aid, furnish aid, afford aid, supply aid, give a helping hand, stretch a hand, lend a helping hand, lend a hand, bear a helping hand, hold out a hand, hold out a helping hand, give one a life, give one a cast, give one a turn, take by the hand, take in tow, help a lame dog over a stile, lend wings to, relieve, rescue, set up, set agoing, set on one's legs, bear through, pull through, give new life to, be the making of, reinforce, reenforce, recruit, set forward, put forward, push forward, give a lift, give a shove, give an impulse to, promote, further, forward, advance expedite, speed, quicken, hasten, support, sustain, uphold, prop, hold up, bolster, cradle, nourish, nurture, nurse, dry nurse, suckle, put out to nurse, manure, cultivate, force, foster, cherish, foment, feed the flame, fan the flame, serve, do service to, tender to, pander to, administer to, subminister to, minister to, tend, attend, wait on, take care of, entertain, smooth the bed of death, oblige, accommodate, consult the wishes of, humor, cheer, encourage, second, stand by, back, back up, pay the piper, abet, work for, make interest for, stick up for, take up the cudgels for, take up the cause of, espouse the cause of, adopt the cause of, advocate, beat up for recruits, press into the service, squire, give moral support to, keep in countenance, countenance, patronize, lend oneself to, lend one's countenance to, smile upon, shine upon, favor, befriend, take in hand, enlist under the banners of, side with, be of use to, subserve, benefit, render a service, conduce.

VB  amount to, come to, mount up to, touch the pocket, draw, draw upon, indorse, issue, utter, discount, back, demonetize, remonetize, fiscalize, monetize, circulate, be in circulation, be out of circulation, mint (coins), coin, print (paper currency), inflate, deflate, debase, devalue, revalue, circulate, put in circulation, withdraw from circulation, exchange currencies, change money, charge interest, pay interest, lose interest.

N  rear, back, posteriority, rear rank, rear guard, background, hinterland, occiput, nape, chine, heels, tail, rump, croup, buttock, posteriors, backside scut, breech, dorsum, loin, dorsal region, lumbar region, hind quarters, aitchbone, natch, natch bone, stern, poop, afterpart, heelpiece, crupper, wake, train, reverse, other side of the shield, back, rear, hind, hinder, hindmost, hindermost, postern, posterior, dorsal, after, caudal, lumbar, mizzen, tergal, behind, in the rear, in the background, behind one's back, at the heels of, at the tail of, at the back of, back to back, after, aft, abaft, astern, sternmost, aback, rearward, ogni medaglia ha il suo rovescio, the other side of the coin, rear, back, posteriority, rear rank, rear guard, background, hinterland, occiput, nape, chine, heels, tail, rump, croup, buttock, posteriors, backside scut, breech, dorsum, loin, dorsal region, lumbar region, hind quarters, aitchbone, natch, natch bone, stern, poop, afterpart, heelpiece, crupper, wake, train, reverse, other side of the shield, back, rear, hind, hinder, hindmost, hindermost, postern, posterior, dorsal, after, caudal, lumbar, mizzen, tergal, behind, in the rear, in the background, behind one's back, at the heels of, at the tail of, at the back of, back to back, after, aft, abaft, astern, sternmost, aback, rearward, ogni medaglia ha il suo rovescio, the other side of the coin.

N  convexity, prominence, projection, swelling, gibbosity, bilge, bulge, protuberance, protrusion, camber, cahot, thank-ye-ma'am, swell, intumescence, tumour, tumor, tubercle, tuberosity, excrescence, hump, hunch, bunch, boss, embossment, hub, hubble, tooth, knob, elbow, process, apophysis, condyle, bulb, node, nodule, nodosity, tongue, dorsum, bump, clump, sugar loaf, bow, mamelon, molar, belly, corporation, pot belly, gut, withers, back, shoulder, lip, flange, pimple, zit, wen, wheel, papula, pustule, pock, proud flesh, growth, sarcoma, caruncle, corn, wart, pappiloma, furuncle, polypus, fungus, fungosity, exostosis, bleb, blister, blain, boil, airbubble, blob, papule, verruca, papilla, nipple, teat, tit, titty, boob, knocker, pap, breast, dug, mammilla, proboscis, nose, neb, beak, snout, nozzle, schnoz, peg, button, stud, ridge, rib, jutty, trunnion, snag, cupola, dome, arch, balcony, eaves, pilaster, relief, relievo, cameo, bassorilievo, mezzorilevo, altorivievo, low relief, bas relief, high relief, hill, cape, promontory, mull, forehead, foreland, point of land, mole, jetty, hummock, ledge, spur, naze, ness, convex, prominent, protuberant, projecting, bossed, embossed, bossy, nodular, bunchy, clavate, clavated, claviform, hummocky, moutonne, mammiliform, papulous, papilose, hemispheric, bulbous, bowed, arched, bold, bellied, tuberous, tuberculous, tumous, cornute, odontoid, lentiform, lenticular, gibbous, club shaped, hubby, hubbly, knobby, papillose, saddle-shaped, selliform, subclavate, torose, ventricose, verrucose, salient, in relief, raised, repousse, bloated, (expanded).

N  regress, regression, retrocession, retrogression, retrograduation, retroaction, reculade, retreat, withdrawal, retirement, remigration, recession, recess, crab-like motion, refluence, reflux, backwater, regurgitation, ebb, return, resilience reflection, reflexion (recoil), flip-flop, volte-face, counter motion, retrograde motion, backward movement, motion in reverse, counter movement, counter march, veering, tergiversation, recidivation, backsliding, fall, deterioration, recidivism, recidivity, reversal, relapse, turning point, receding, retrograde, retrogressive, regressive, refluent, reflex, recidivous, resilient, crab-like, balky, reactionary, back, backwards, reflexively, to the right about, a reculons, a rebours, revenons a nos moutons, as you were.