1.  The back, or top of the back; a crest. Hudibras. [1913 Webster]

2.  A range of hills or mountains, or the upper part of such a range; any extended elevation between valleys. Shak. [1913 Webster]
"Part rise crystal wall, or ridge direct." [1913 Webster]

3.  A raised line or strip, as of ground thrown up by a plow or left between furrows or ditches, or as on the surface of metal, cloth, or bone, etc. [1913 Webster]

4.  The intersection of two surface forming a salient angle, especially the angle at the top between the opposite slopes or sides of a roof or a vault. [1913 Webster]

5.  The highest portion of the glacis proceeding from the salient angle of the covered way. Stocqueler. [1913 Webster]

1.  To form a ridge of; to furnish with a ridge or ridges; to make into a ridge or ridges. [1913 Webster]
"Bristles ranged like those that ridge the back
Of chafed wild boars." [1913 Webster]

2.  To form into ridges with the plow, as land. [1913 Webster]

3.  To wrinkle. Cowper. [1913 Webster]

ridge, n. & v.
--n.
1 the line of the junction of two surfaces sloping upwards towards each other (the ridge of a roof).
2 a long narrow hilltop, mountain range, or watershed.
3 any narrow elevation across a surface.
4 Meteorol. an elongated region of high barometric pressure.
5 Agriculture a raised strip of arable land, usu. one of a set separated by furrows.
6 Hort. a raised hotbed for melons etc.
--v.
1 tr. mark with ridges.
2 tr. Agriculture break up (land) into ridges.
3 tr. Hort. plant (cucumbers etc.) in ridges.
4 tr. & intr. gather into ridges.

Idiom:
ridge-piece (or -tree) a beam along the ridge of a roof. ridge-pole
1 the horizontal pole of a long tent.
2 = ridge-piece. ridge-tile a tile used in making a roof-ridge.

Derivative:
ridgy adj.

Etymology:
OE hrycg f. Gmc

N  narrowness, thinness, narrowness, closeness, exility, exiguity, line, hair's breadth, finger's breadth, strip, streak, vein, monolayer, epitaxial deposition, thinness, tenuity, emaciation, macilency, marcor, shaving, slip, thread paper, skeleton, shadow, anatomy, spindleshanks, lantern jaws, mere skin and bone, middle constriction, stricture, neck, waist, isthmus, wasp, hourglass, ridge, ghaut, ghat, pass, ravine, narrowing, coarctation, angustation, tapering, contraction, narrow, close, slender, thin, fine, thread-like, finespun, gossamer, paper-thin, taper, slim, slight-made, scant, scanty, spare, delicate, incapacious, contracted, unexpanded &c (expand), slender as a thread, emaciated, lean, meager, gaunt, macilent, lank, lanky, weedy, skinny, scrawny slinky, starved, starveling, herring gutted, worn to a shadow, lean as a rake, thin as a lath, thin as a whipping post, thin as a wafer, hatchet-faced, lantern-jawed, attenuated, shriveled, extenuated, tabid, marcid, barebone, rawboned, monomolecular.

N  height, altitude, elevation, eminence, pitch, loftiness, sublimity, tallness, stature, procerity, prominence, colossus, giant, grenadier, giraffe, camelopard, mount, mountain, hill alto, butte, monticle, fell, knap, cape, headland, foreland, promontory, ridge, hog's back, dune, rising ground, vantage ground, down, moor, moorland, Alp, uplands, highlands, heights, knob, loma, pena, picacho, tump, knoll, hummock, hillock, barrow, mound, mole, steeps, bluff, cliff, craig, tor, peak, pike, clough, escarpment, edge, ledge, brae, dizzy height, tower, pillar, column, obelisk, monument, steeple, spire, minaret, campanile, turret, dome, cupola, skyscraper, pole, pikestaff, maypole, flagstaff, top mast, topgallant mast, ceiling, high water, high tide, flood tide, spring tide, altimetry, batophobia, satellite, spy-in-the-sky, high, elevated, eminent, exalted, lofty, tall, gigantic, Patagonian, towering, beetling, soaring, hanging (gardens), elevated, upper, highest, high reaching, insessorial, perching, upland, moorland, hilly, knobby, mountainous, alpine, subalpine, heaven kissing, cloudtopt, cloudcapt, cloudtouching, aerial, overhanging, incumbent, overlying, superincumbent, supernatant, superimposed, prominent, tall as a maypole, tall as a poplar, tall as a steeple, lanky, on high, high up, aloft, up, above, aloof, overhead, airwind, upstairs, abovestairs, in the clouds, on tiptoe, on stilts, on the shoulders of, over head and ears, breast high, over, upwards, from top to bottom, e meglio cader dalle finistre che dal tetto.

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).

alveolar ridge, blue ridge, blue ridge mountains, gum ridge, mid-atlantic ridge, moving ridge, ridge rope, ridge tile, superciliary ridge, supraorbital ridge