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. conduit, channel, duct, watercourse, race, head race, tail race, abito, aboideau, aboiteau, bito, acequia, acequiador, acequiamadre, arroyo, adit, aqueduct, canal, trough, gutter, pantile, flume, ingate, runner, lock-weir, tedge, vena, dike, main, gully, moat, ditch, drain, sewer, culvert, cloaca, sough, kennel, siphon, piscina, pipe, funnel, tunnel, water pipe, waste pipe, emunctory, gully hole, artery, aorta, pore, spout, scupper, adjutage, ajutage, hose, gargoyle, gurgoyle, penstock, weir, flood gate, water gate, sluice, lock, valve, rose, waterworks, pipeline

Adj. vascular