N. 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

V. open, ope, gape, yawn, bilge, fly open, perforate, pierce, empierce|, tap, bore, drill, mine, tunnel, transpierce, transfix, enfilade, impale, spike, spear, gore, spit, stab, pink, puncture, lance, stick, prick, riddle, punch, stave in, cut a passage through, make way for, make room for, uncover, unclose, unrip, lay open, cut open, rip open, throw open, pop open, blow open, pry open, tear open, pull open

Adj. 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

N. 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, 3, imperfect fluids