1.  door(n = noun.artifact) - a swinging or sliding barrier that will close the entrance to a room or building or vehicle; "he knocked on the door"; "he slammed the door as he left"
is a kind of movable barrier
is a part of door, doorway, room access, threshold
has parts: lock
has particulars: car door, cargo door, double door, fire door, french door, interior door, revolver, revolving door, screen, screen door, sliding door, storm door, swing door, swinging door, trap door

2.  door(n = noun.artifact) doorway, room access, threshold - the entrance (the space in a wall) through which you enter or leave a room or building; the space that a door can close; "he stuck his head in the doorway"
is a kind of entrance, entranceway, entree, entry, entryway
is a part of wall
has parts: case, casing, door, doorcase, doorframe, doorsill, doorstep, threshold
has particulars: exterior door, outside door

3.  door(n = noun.attribute) - anything providing a means of access (or escape); "we closed the door to Haitian immigrants"; "education is the door to success"
is a kind of access, accession, admission, admittance, entree
has particulars: open door

4.  door(n = noun.artifact) - a structure where people live or work (usually ordered along a street or road); "the office next door"; "they live two doors up the street from us"
is a kind of construction, structure

5.  door(n = noun.artifact) - a room that is entered via a door; "his office is the third door down the hall on the left"
is a kind of room

door, n.
1 a a hinged, sliding, or revolving barrier for closing and opening an entrance to a building, room, cupboard, etc. b this as representing a house etc. (lives two doors away).
2 a an entrance or exit; a doorway. b a means of access or approach.

Idiom:
close the door to exclude the opportunity for. door-case (or -frame) the structure into which a door is fitted. door-head the upper part of a door-case. door-keeper = DOORMAN. door-plate a plate on the door of a house or room bearing the name of the occupant. door-to-door (of selling etc.) done at each house in turn. lay (or lie) at the door of impute (or be imputable) to. leave the door open ensure that an option remains available. next door in or to the next house or room. next door to
1 in the next house to.
2 nearly, almost, near to. open the door to create an opportunity for. out of doors in or into the open air.

Derivative:
doored adj. (also in comb.).

Etymology:
OE duru, dor f. Gmc

N  method, way, manner, wise, gait, form, mode, fashion, tone, guise, modus operandi, MO, procedure, path, road, route, course, line of way, line of road, trajectory, orbit, track, beat, tack, steps, stair, staircase, flight of stairs, ladder, stile, perron, bridge, footbridge, viaduct, pontoon, steppingstone, plank, gangway, drawbridge, pass, ford, ferry, tunnel, pipe, door, gateway, channel, passage, avenue, means of access, approach, adit, artery, lane, loan, alley, aisle, lobby, corridor, back-door, back-stairs, secret passage, covert way, vennel, roadway, pathway, stairway, express, thoroughfare, highway, turnpike, freeway, royal road, coach road, broad highway, King's highway, Queen's highway, beaten track, beaten path, horse road, bridle road, bridle track, bridle path, walk, trottoir, footpath, pavement, flags, sidewalk, crossroad, byroad, bypath, byway, cut, short cut carrefour, private road, occupation road, highways and byways, railroad, railway, tram road, tramway, towpath, causeway, canal, street, speedway, adv, how, in what way, in what manner, by what mode, so, in this way, after this fashion, one way or another, anyhow, somehow or other, by way of, via, in transitu, on the high road to, hae tibi erunt artes.

N  beginning, commencement, opening, outset, incipience, inception, inchoation, introduction, alpha, initial, inauguration, debut, le premier pas, embarcation, rising of the curtain, maiden speech, outbreak, onset, brunt, initiative, move, first move, narrow end of the wedge, thin end of the wedge, fresh start, new departure, origin, source, rise, bud, germ, egg, rudiment, genesis, primogenesis, birth, nativity, cradle, infancy, start, inception, creation, starting point, dawn, evolution, title-page, head, heading, van, caption, fatihah, entrance, entry, inlet, orifice, mouth, chops, lips, porch, portal, portico, propylon, door, gate, gateway, postern, wicket, threshold, vestibule, propylaeum, skirts, border, first stage, first blush, first glance, first impression, first sight, rudiments, elements, outlines, grammar, alphabet, ABC, beginning, initial, initiatory, initiative, inceptive, introductory, incipient, proemial, inaugural, inchoate, inchoative, embryonic, rudimental, primogenial, primeval, primitive, primordial, aboriginal, natal, nascent, first, foremost, leading, maiden, begun, just begun, at the beginning, in the beginning first, in the first place, imprimis, first and foremost, in limine, in the bud, in embryo, in its infancy, from the beginning, from its birth, ab initio, ab ovo, ab incunabilis, ab origine, let's get going!, let's get this show on the road!, up and at 'em!, aller Anfang ist schwer, dimidium facti qui coepit habet, omnium rerum principia parva sunt.

N  covering, cover, baldachin, baldachino, baldaquin, canopy, tilt, awning, tent, marquee, tente d'abri, umbrella, parasol, sunshade, veil (shade), shield, roof, ceiling, thatch, tile, pantile, pentile, tiling, slates, slating, leads, barrack, plafond, planchment, tiling, shed, top, lid, covercle, door, operculum, bulkhead, bandage, plaster, lint, wrapping, dossil, finger stall, coverlet, counterpane, sheet, quilt, tarpaulin, blanket, rug, drugget, housing, antimacassar, eiderdown, numdah, pillowcase, pillowslip, linoleum, saddle cloth, blanket cloth, tidy, tilpah, apishamore, integument, tegument, skin, pellicle, fleece, fell, fur, leather, shagreen, hide, pelt, peltry, cordwain, derm, robe, buffalo robe, cuticle, scarfskin, epidermis, clothing, mask, peel, crust, bark, rind, cortex, husk, shell, coat, eggshell, glume, capsule, sheath, sheathing, pod, cod, casing, case, theca, elytron, elytrum, involucrum, wrapping, wrapper, envelope, vesicle, corn husk, corn shuck, dermatology, conchology, testaceology, inunction, incrustation, superimposition, superposition, obduction, scale, veneer, facing, overlay, plate, silver plate, gold plate, copper plate, engobe, ormolu, Sheffield plate, pavement, coating, paint, varnish, plating, barrel plating, anointing, enamel, epitaxial deposition, vapor deposition, ground, whitewash, plaster, spackel, stucco, compo, cerement, ointment, covering, superimposed, overlaid, plated, cutaneous, dermal, cortical, cuticular, tegumentary, skinny, scaly, squamous, covered, imbricated, loricated, armor plated, ironclad, under cover, cowled, cucullate, dermatoid, encuirassed, hooded, squamiferous, tectiform, vaginate.

N  edge, verge, brink, brow, brim, margin, border, confine, skirt, rim, flange, side, mouth, jaws, chops, chaps, fauces, lip, muzzle, threshold, door, porch, portal, coast, shore, frame, fringe, flounce, frill, list, trimming, edging, skirting, hem, selvedge, welt, furbelow, valance, gimp, border, marginal, skirting, labial, labiated, marginated.

N  inclosure, envelope, case, wrapper, girdle, pen, fold, pen fold, in fold, sheep fold, paddock, pound, corral, yard, net, seine net, wall, hedge, hedge row, espalier, fence, pale, paling, balustrade, rail, railing, quickset hedge, park paling, circumvallation, enceinte, ring fence, barrier, barricade, gate, gateway, bent, dingle, door, hatch, cordon, prison, dike, dyke, ditch, fosse, moat.

N  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!.

N  ingress, entrance, entry, introgression, influx, intrusion, inroad, incursion, invasion, irruption, ingression, penetration, interpenetration, illapse, import, infiltration, immigration, admission, insinuation, insertion, inlet, way in, mouth, door, barway, path, conduit, immigrant, incoming.

N  egress, exit, issue, emersion, emergence, outbreak, outburst, eruption, proruption, emanation, egression, evacuation, exudation, transudation, extravasation, perspiration, sweating, leakage, percolation, distillation, oozing, gush, outpour, outpouring, effluence, effusion, effluxion, drain, dribbling, defluxion, drainage, outcome, output, discharge, export, expatriation, emigration, remigration, debouch, debouche, emunctory, exodus, emigrant, outlet, vent, spout, tap, sluice, floodgate, pore, vomitory, outgate, sally port, way out, mouth, door, path, conduit, airpipe, effused, outgoing.

accordion door, back door, barn door, bi-fold door, car door, cargo door, door guard, door latch, door prize, double door, dutch door, exterior door, fire door, folding door, french door, front door, half door, hatchback door, interior door, louvered door, next door, open door, outside door, revolving door, screen door, service door, show the door, side door, sliding door, stage door, storm door, swing door, swinging door, trap door, wicket door