abysm, abyss, arroyo, box canyon, breach, break, canyon, cavity, chap, chasm, check, chimney
corner, chink, chute, cleft, cleuch, clough, col, coulee, couloir, country rock, crack, cranny, crevasse, crevice, cut, cwm, defile, dell, deposit, dike, ditch, donga, draw, excavation, fault, fender, fire screen, fireboard, fireguard, fireplace, fireside, fissure, flaw, flue, flue pipe, flume, fracture, fumarole, funnel, furrow, gangue, gap, gape, gash, gorge, groove, gulch, gulf, gully, hearth, hearthstone, hob, hole, hub, incision, ingle, inglenook, ingleside, joint, kloof, leak, lode, lodestuff, matrix, mineral deposit, moat, notch, nullah, opening, ore bed, pass, passage, pay dirt, ravine, rent, rift, rime, rupture, scissure, seam, shoot, slit, slot, smokehole, smokeshaft, smokestack, split, stack, stock, stovepipe, trench, valley, vein, void, wadi
opening, hole, foramen, puncture, perforation, fontanel, transforation, pinhole, keyhole, loophole, porthole, peephole, mousehole, pigeonhole, eye of a needle, eyelet, slot, opening, aperture, apertness, hiation, yawning, oscitancy, dehiscence, patefaction, pandiculation, chasm, embrasure, window, casement, abatjour, light, sky light, fan light, lattice, bay window, bow window, oriel, dormer, lantern, outlet, inlet, vent, vomitory, embouchure, orifice, mouth, sucker, muzzle, throat, gullet, weasand, wizen, nozzle, placket, portal, porch, gate, ostiary, postern, wicket, trapdoor, hatch, door, arcade, cellarway, driveway, gateway, doorway, hatchway, gangway, lich gate, way, path, thoroughfare, channel, passage, passageway, tube, pipe, water pipe, air pipe, vessel, tubule, canal, gut, fistula, adjutage, ajutage, ostium, smokestack, chimney
, flue, tap, funnel, gully, tunnel, main, mine, pit, adit, shaft, gallery, alley, aisle, glade, vista, bore, caliber, pore, blind orifice, fulgurite, thundertube, porousness, porosity, sieve, cullender, colander, cribble, riddle, screen, honeycomb, apertion, perforation, piercing, terebration, empalement, pertusion, puncture, acupuncture, penetration, key, opener, master key, password, combination, passe- partout, open, perforated, perforate, wide open, ajar, unclosed, unstopped, oscitant, gaping, yawning, patent, tubular, cannular, fistulous, pervious, permeable, foraminous, vesicular, vasicular, porous, follicular, cribriform, honeycombed, infundibular, riddled, tubulous, tubulated, piped, tubate, opening, aperient, Int, open sesame!.
airpipe, air pipe, air tube, airhole, blowhole, breathinghole, venthole, shaft, flue, chimney
, funnel, vent, nostril, nozzle, throat, weasand, trachea, bronchus, bronchia, larynx, tonsils, windpipe, spiracle, ventiduct, ventilator, louvre, jalousie, Venetian blinds, blowpipe, pipe, jhilmil, smokestack, screen, window screen, ' artificial lung, iron lung, heart and lung machine.