Source : Webster's Revised Unabridged Dictionary (1913)

Door \Door\, n. [OE. dore, dure, AS. duru; akin to OS. dura,
   dor, D. deur, OHG. turi, door, tor gate, G. th["u]r, thor,
   Icel. dyrr, Dan. d["o]r, Sw. d["o]rr, Goth. daur, Lith.
   durys, Russ. dvere, Olr. dorus, L. fores, Gr. ?; cf. Skr.
   dur, dv[=a]ra. ????. Cf. {Foreign}.]
   1. An opening in the wall of a house or of an apartment, by
      which to go in and out; an entrance way.

            To the same end, men several paths may tread, As
            many doors into one temple lead.      --Denham.

   2. The frame or barrier of boards, or other material, usually
      turning on hinges, by which an entrance way into a house
      or apartment is closed and opened.

            At last he came unto an iron door That fast was
            locked.                               --Spenser.

   3. Passage; means of approach or access.

            I am the door; by me if any man enter in, he shall
            be saved.                             --John x. 9.

   4. An entrance way, but taken in the sense of the house or
      apartment to which it leads.

            Martin's office is now the second door in the
            street.                               --Arbuthnot.

   {Blank door}, {Blind door}, etc. (Arch.) See under {Blank},
      {Blind}, etc.

   {In doors}, or {Within doors}, within the house.

   {Next door to}, near to; bordering on.

            A riot unpunished is but next door to a tumult.
                                                  --L'Estrange.
      

   {Out of doors}, or {Without doors}, and, colloquially, {Out
   doors}, out of the house; in open air; abroad; away; lost.

            His imaginary title of fatherhood is out of doors.
                                                  --Locke.

   {To lay (a fault, misfortune, etc.) at one's door}, to charge
      one with a fault; to blame for.

   {To lie at one's door}, to be imputable or chargeable to.

            If I have failed, the fault lies wholly at my door.
                                                  --Dryden.

   Note: Door is used in an adjectival construction or as the
         first part of a compound (with or without the hyphen),
         as, door frame, doorbell or door bell, door knob or
         doorknob, door latch or doorlatch, door jamb, door
         handle, door mat, door panel.