coulter(n = noun.artifact) colter - a sharp steel wedge that precedes the plow and cuts vertically through the soil;
is a kind of wedge
is a part of moldboard plow, mouldboard plough

   Same as Colter. [1913 Webster]

coulter, n. (US colter) a vertical cutting blade fixed in front of a ploughshare.

Etymology:
OE f. L culter

N  sharpness, acuity, acumination, spinosity, point, spike, spine, spicule, spiculum, needle, hypodermic needle, tack, nail, pin, prick, prickle, spur, rowel, barb, spit, cusp, horn, antler, snag, tag thorn, bristle, Adam's needle, bear grass, tine, yucca, nib, tooth, tusk, spoke, cog, ratchet, crag, crest, arete, cone peak, sugar loaf, pike, aiguille, spire, pyramid, steeple, beard, chevaux de frise, porcupine, hedgehog, brier, bramble, thistle, comb, awn, beggar's lice, bur, burr, catchweed, cleavers, clivers, goose, grass, hairif, hariff, flax comb, hackle, hatchel, heckle, wedge, knife edge, cutting edge, blade, edge tool, cutlery, knife, penknife, whittle, razor, razor blade, safety razor, straight razor, electric razor, scalpel, bistoury, lancet, plowshare, coulter, colter, hatchet, ax, pickax, mattock, pick, adze, gill, billhook, cleaver, cutter, scythe, sickle, scissors, shears, pruning shears, cutters, wire cutters, nail clipper, paper cutter, sword, bodkin, belduque, bowie knife, paring knife, bushwhacker, drawing knife, drawing shave, microtome, chisel, screwdriver blade, flint blade, guillotine, sharpener, hone, strop, grindstone, whetstone, novaculite, steel, emery, sharp, keen, acute, acicular, aciform, aculeated, acuminated, pointed, tapering, conical, pyramidal, mucronate, mucronated, spindle shaped, needle shaped, spiked, spiky, ensiform, peaked, salient, cusped, cuspidate, cuspidated, cornute, cornuted, cornicultate, prickly, spiny, spinous, spicular, thorny, bristling, muricated, pectinated, studded, thistly, briary, craggy, snaggy, digitated, two-edged, fusiform, dentiform, denticulated, toothed, odontoid, starlike, stellated, stelliform, sagittate, sagittiform, arrowheaded, arrowy, barbed, spurred, acinaciform, apiculate, apiculated, aristate, awned, awny, bearded, calamiform, cone-shaped, coniform, crestate, echinate, gladiate, lanceolate, lanciform, awl, awl-shaped, lance-shaped, awl- shaped, scimitar-shaped, sword-shaped, setarious, spinuliferous, subulate, tetrahedral, xiphoid, cutting, sharp edged, knife edged, sharp as a razor, keen as a razor, sharp as a needle, sharp as a tack, sharpened, set.