1.  backbone(n = noun.cognition) anchor, keystone, linchpin, lynchpin, mainstay - a central cohesive source of support and stability; "faith is his anchor"; "the keystone of campaign reform was the ban on soft money"; "he is the linchpin of this firm"
is a kind of support

2.  backbone(n = noun.attribute) grit, gumption, guts, moxie, sand - fortitude and determination; "he didn't have the guts to try it"
is a kind of fortitude

3.  backbone(n = noun.body) back, 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"
is a kind of skeletal structure
is a part of axial skeleton
has parts: canalis vertebralis, spinal canal, vertebral canal, coccyx, tail bone, vertebra, intervertebral disc, intervertebral disk
has particulars: notochord, chine

4.  backbone(n = noun.artifact) spine - the part of a book's cover that encloses the inner side of the book's pages and that faces outward when the book is shelved; "the title and author were printed on the spine of the book"
is a kind of part, portion
is a part of book, volume

5.  backbone(n = noun.artifact) Array - the part of a network that connects other networks together; "the backbone is the part of a communication network that carries the heaviest traffic"
is a kind of connecter, connection, connective, connector, connexion
is a part of mesh, meshing, meshwork, net, network

1.  The column of bones in the back which sustains and gives firmness to the frame; the spine; the vertebral or spinal column. [1913 Webster]

2.  Anything like , or serving the purpose of, a backbone. [1913 Webster]
"The lofty mountains on the north side compose the granitic axis, or backbone of the country." [1913 Webster]
"We have now come to the backbone of our subject." [1913 Webster]

3.  Firmness; moral principle; steadfastness. [1913 Webster]
"Shelley's thought never had any backbone." [1913 Webster]

backbone, n.
1 the spine.
2 the main support of a structure.
3 firmness of character.
4 US the spine of a book.

N  resolution, determination, will, iron will, unconquerable will, will of one's own, decision, resolution, backbone, clear grit, true grit, grit, sand, strength of mind, strength of will, resolve, firmness, energy, manliness, vigor, game, pluck, resoluteness, zeal, aplomb, desperation, devotion, devotedness, mastery over self, self control, self command, self possession, self reliance, self government, self restraint, self conquest, self denial, moral courage, moral strength, perseverance, tenacity, obstinacy, bulldog, British lion, resolved, determined, strong-willed, strong-minded, resolute, self-possessed, decided, definitive, peremptory, tranchant, unhesitating, unflinching, unshrinking, firm, iron, gritty, indomitable, game to the backbone, inexorable, relentless, not to be shaken, not to be put down, tenax propositi, inflexible, obstinate, steady, earnest, serious, set upon, bent upon, intent upon, steel against, proof against, in utrumque paratus, resolutely, in earnest, in good earnest, seriously, joking apart, earnestly, heart and soul, on one's mettle, manfully, like a man, with a high hand, with a strong hand, at any rate, at any risk, at any hazard, at any price, at any cost, at any sacrifice, at all hazards, at all risks, at all events, a' bis ou a blanc, cost what it may, coute, a tort et a travers, once for all, neck or nothing, rain or shine, spes sibi quisque, celui qui veut celui-la peut, chi non s'arrischia non guadagna, frangas non flectes, manu forti, tentanda via est.

N  perseverance, continuance, permanence, firmness, constancy, steadiness, singleness of purpose, tenacity of purpose, persistence, plodding, patience, sedulity, pertinacy, pertinacity, pertinaciousness, iteration, bottom, game, pluck, stamina, backbone, grit, indefatigability, indefatigableness, bulldog courage, persevering, constant, steady, steadfast, undeviating, unwavering, unfaltering, unswerving, unflinching, unsleeping, unflagging, undrooping, steady as time, unrelenting, unintermitting, unremitting, plodding, industrious, strenuous, pertinacious, persisting, persistent, solid, sturdy, staunch, stanch, true to oneself, unchangeable, unconquerable, indomitable, game to the last, indefatigable, untiring, unwearied, never tiring, through evil report and good report, through thick and thin, through fire and water, per fas et nefas, without fail, sink or swim, at any price, vogue la galere, never say die, give it the old college try, vestigia nulla retrorsum, aut vincer aut mori, la garde meurt et ne se rend pas, tout vient a temps pour qui sait attendre.

N  intrinsicality, inbeing, inherence, inhesion, subjectiveness, ego, egohood, essence, noumenon, essentialness, essential part, quintessence, incarnation, quiddity, gist, pith, marrow, core, sap, lifeblood, backbone, heart, soul, important part, principle, nature, constitution, character, type, quality, crasis, diathesis, habit, temper, temperament, spirit, humor, grain, disposition, endowment, capacity, capability, moods, declensions, features, aspects, peculiarities, idiosyncrasy, oddity, idiocrasy, diagnostics, derived from within, subjective, intrinsic, intrinsical, fundamental, normal, implanted, inherent, essential, natural, innate, inborn, inbred, ingrained, inwrought, coeval with birth, genetous, haematobious, syngenic, radical, incarnate, thoroughbred, hereditary, inherited, immanent, congenital, congenite, connate, running in the blood, ingenerate, ingenite, indigenous, in the grain, bred in the bone, instinctive, inward, internal, to the manner born, virtual, characteristic, invariable, incurable, incorrigible, ineradicable, fixed, intrinsically, at bottom, in the main, in effect, practically, virtually, substantially, au fond, fairly, character is higher than intellect, come give us a taste of your quality, magnos homines virtute metimur non fortuna, non numero haec judicantur sed pondere, vital spark of heavenly flame.

N  affections, affect, character, qualities, disposition, nature, spirit, tone, temper, temperament, diathesis, idiosyncrasy, cast of mind, cast of soul, habit of mind, habit of soul, frame of mind, frame of soul, predilection, turn, natural turn of mind, bent, bias, predisposition, proneness, proclivity, propensity, propenseness, propension, propendency, vein, humor, mood, grain, mettle, sympathy, soul, heart, breast, bosom, inner man, heart's core, heart's strings, heart's blood, heart of hearts, bottom of one's heart, penetralia mentis, secret and inmost recesses of the heart, cockles of one's heart, inmost heart, inmost soul, backbone, passion, pervading spirit, ruling passion, master passion, furore, fullness of the heart, heyday of the blood, flesh and blood, flow of soul, energy, fervor, fire, force, affected, characterized, formed, molded, cast, attempered, tempered, framed, predisposed, prone, inclined, having a bias, tinctured with, imbued with, penetrated with, eaten up with, inborn, inbred, ingrained, deep-rooted, ineffaceable, inveterate, pathoscopic, congenital, dyed in the wool, implanted by nature, inherent, in the grain, affective, in one's heart, at heart, heart and soul, affection is a coal that must be cool'd else suffe.

N  courage, bravery, valor, resoluteness, boldness, spirit, daring, gallantry, intrepidity, contempt of danger, defiance of danger, derring-do, audacity, rashness, dash, defiance, confidence, self-reliance, manliness, manhood, nerve, pluck, mettle, game, heart, heart of grace, spunk, guts, face, virtue, hardihood, fortitude, intestinal fortitude, firmness, heart of oak, bottom, backbone, spine, resolution, bulldog courage, prowess, heroism, chivalry, exploit, feat, achievement, heroic deed, heroic act, bold stroke, man, man of mettle, hero, demigod, Amazon, Hector, lion, tiger, panther, bulldog, gamecock, fighting-cock, bully, fire eater, courageous, brave, valiant, valorous, gallant, intrepid, spirited, spiritful, high-spirited, high-mettled, mettlesome, plucky, manly, manful, resolute, stout, stout-hearted, iron-hearted, lion-hearted, heart of oak, Penthesilean, bold, bold-spirited, daring, audacious, fearless, dauntless, dreadless, aweless, undaunted, unappalled, undismayed, unawed, unblanched, unabashed, unalarmed, unflinching, unshrinking, unblanching, unapprehensive, confident, self-reliant, bold as a lion, bold as brass, enterprising, adventurous, venturous, venturesome, dashing, chivalrous, soldierly, heroic, fierce, savage, pugnacious, strong-minded, hardy, doughty, firm, determined, dogged, indomitable, up to, up to the scratch, upon one's mettle, reassured, unfeared, undreaded, one's blood being up, courage sans peur, fortes fortuna adjuvat, have I not in my time heard lions roar, I dare do all that may become a man, male vincetis sed vincite, omne solum forti patria, self-trust is the essence of heroism, stimulos dedit oemula virtus, strong and great, a hero, teloque animus proestantior omni, there, is always safety in valor, virtus ariete fortier.

N  support, ground, foundation, base, basis, terra firma, bearing, fulcrum, bait, caudex crib, point d'appui, pou sto, purchase footing, hold, locus standi, landing place, landing stage, stage, platform, block, rest, resting place, groundwork, substratum, riprap, sustentation, subvention, floor, supporter, aid, prop, stand, anvil, fulciment, cue rest, jigger, monkey, stay, shore, skid, rib, truss, bandage, sleeper, stirrup, stilts, shoe, sole, heel, splint, lap, bar, rod, boom, sprit, outrigger, ratlings, staff, stick, crutch, alpenstock, baton, staddle, bourdon, cowlstaff, lathi, mahlstick, post, pillar, shaft, thill, column, pilaster, pediment, pedicle, pedestal, plinth, shank, leg, socle, zocle, buttress, jamb, mullion, abutment, baluster, banister, stanchion, balustrade, headstone, upright, door post, jamb, door jamb, frame, framework, scaffold, skeleton, beam, rafter, girder, lintel, joist, travis, trave, corner stone, summer, transom, rung, round, step, sill, angle rafter, hip rafter, cantilever, modillion, crown post, king post, vertebra, columella, backbone, keystone, axle, axletree, axis, arch, mainstay, trunnion, pivot, rowlock, peg, tiebeam, thole pin, board, ledge, shelf, hob, bracket, trevet, trivet, arbor, rack, mantel, mantle piece, mantleshelf, slab, console, counter, dresser, flange, corbel, table, trestle, shoulder, perch, horse, easel, desk, clotheshorse, hatrack, retable, teapoy, seat, throne, dais, divan, musnud, chair, bench, form, stool, sofa, settee, stall, arm chair, easy chair, elbow chair, rocking chair, couch, fauteuil, woolsack, ottoman, settle, squab, bench, aparejo, faldstool, horn, long chair, long sleeve chair, morris chair, lamba chauki, lamba kursi, saddle, pannel, pillion, side saddle, pack saddle, pommel, bed, berth, pallet, tester, crib, cot, hammock, shakedown, trucklebed, cradle, litter, stretcher, bedstead, four poster, French bed, bunk, kip, palang, bedding, bichhona, mattress, paillasse, pillow, bolster, mat, rug, cushion, footstool, hassock, tabouret, tripod, monopod, Atlas, Persides, Atlantes, Caryatides, Hercules, supporting, supported, fundamental, dorsigerous, astride on, straddle.

N  interiority, inside, interior, interspace, subsoil, substratum, intrados, contents, substance, pith, marrow, backbone, heart, bosom, breast, abdomen, vitals, viscera, entrails, bowels, belly, intestines, guts, chitterings, womb, lap, penetralia, recesses, innermost recesses, cave, interior, internal, inner, inside, inward, intraregarding, inmost, innermost, deep seated, gut, intestine, intestinal, inland, subcutaneous, abdominal, coeliac, endomorphic, interstitial, inwrought, inclosed, home, domestic, indoor, intramural, vernacular, endemic, internally, inwards, within, in, inly, here in, there in, where in, ab intra, withinside, in doors, within doors, at home, in the bosom of one's family.

N  centrality, centricalness, center, middle, focus, core, kernel, nucleus, nucleolus, heart, pole axis, bull's eye, nave, navel, umbilicus, backbone, marrow, pith, vertebra, vertebral column, hotbed, concentration, centralization, symmetry, center of gravity, center of pressure, center of percussion, center of oscillation, center of buoyancy, metacenter, central, centrical, middle, azygous, axial, focal, umbilical, concentric, middlemost, rachidian, spinal, vertebral, middle, midst, centrally.