The Collaborative International Dictionary of English v.0.48:

Old \Old\, a. [Compar. Older; superl. Oldest.] [OE. old,
   ald, AS. ald, eald; akin to D. oud, OS. ald, OFries. ald,
   old, G. alt, Goth. alpeis, and also to Goth. alan to grow up,
   Icel. ala to bear, produce, bring up, L. alere to nourish.
   Cf. Adult, Alderman, Aliment, Auld, Elder.]
   [1913 Webster]
   1. Not young; advanced far in years or life; having lived
      till toward the end of the ordinary term of living; as, an
      old man; an old age; an old horse; an old tree.
      [1913 Webster]

            Let not old age disgrace my high desire. --Sir P.
                                                  Sidney.
      [1913 Webster]

            The melancholy news that we grow old. --Young.
      [1913 Webster]

   2. Not new or fresh; not recently made or produced; having
      existed for a long time; as, old wine; an old friendship.
      "An old acquaintance." --Camden.
      [1913 Webster]

   3. Formerly existing; ancient; not modern; preceding;
      original; as, an old law; an old custom; an old promise.
      "The old schools of Greece." --Milton. "The character of
      the old Ligurians." --Addison.
      [1913 Webster]

   4. Continued in life; advanced in the course of existence;
      having (a certain) length of existence; -- designating the
      age of a person or thing; as, an infant a few hours old; a
      cathedral centuries old.
      [1913 Webster]

            And Pharaoh said unto Jacob, How old art thou?
                                                  --Cen. xlvii.
                                                  8.
      [1913 Webster]

   Note: In this use old regularly follows the noun that
         designates the age; as, she was eight years old.
         [1913 Webster]

   5. Long practiced; hence, skilled; experienced; cunning; as,
      an old offender; old in vice.
      [1913 Webster]

            Vane, young in years, but in sage counsel old.
                                                  --Milton.
      [1913 Webster]

   6. Long cultivated; as, an old farm; old land, as opposed to
      new land, that is, to land lately cleared.
      [1913 Webster]

   7. Worn out; weakened or exhausted by use; past usefulness;
      as, old shoes; old clothes.
      [1913 Webster]

   8. More than enough; abundant. [Obs.]
      [1913 Webster]

            If a man were porter of hell gate, he should have
            old turning the key.                  --Shak.
      [1913 Webster]

   9. Aged; antiquated; hence, wanting in the mental vigor or
      other qualities belonging to youth; -- used disparagingly
      as a term of reproach.
      [1913 Webster]

   10. Old-fashioned; wonted; customary; as of old; as, the good
       old times; hence, colloquially, gay; jolly.
       [1913 Webster]

   11. Used colloquially as a term of cordiality and
       familiarity. "Go thy ways, old lad." --Shak.
       [1913 Webster]

   Old age, advanced years; the latter period of life.

   Old bachelor. See Bachelor, 1.

   Old Catholics. See under Catholic.

   Old English. See under English. n., 2.

   Old Nick, Old Scratch, the devil.

   Old lady (Zool.), a large European noctuid moth (Mormo
      maura).

   Old maid.
       (a) A woman, somewhat advanced in years, who has never
           been married; a spinster.
       (b) (Bot.) A West Indian name for the pink-flowered
           periwinkle (Vinca rosea).
       (c) A simple game of cards, played by matching them. The
           person with whom the odd card is left is the old
           maid.

   Old man's beard. (Bot.)
       (a) The traveler's joy (Clematis Vitalba). So named
           from the abundant long feathery awns of its fruit.
       (b) The Tillandsia usneoides. See Tillandsia.

   Old man's head (Bot.), a columnar cactus (Pilocereus
      senilis), native of Mexico, covered towards the top with
      long white hairs.

   Old red sandstone (Geol.), a series of red sandstone rocks
      situated below the rocks of the Carboniferous age and
      comprising various strata of siliceous sandstones and
      conglomerates. See Sandstone, and the Chart of
      Geology.

   Old school, a school or party belonging to a former time,
      or preserving the character, manner, or opinions of a
      former time; as, a gentleman of the old school; -- used
      also adjectively; as, Old-School Presbyterians.

   Old sledge, an old and well-known game of cards, called
      also all fours, and high, low, Jack, and the game.

   Old squaw (Zool.), a duck (Clangula hyemalis) inhabiting
      the northern parts of both hemispheres. The adult male is
      varied with black and white and is remarkable for the
      length of its tail. Called also longtailed duck, south
      southerly, callow, hareld, and old wife.

   Old style. (Chron.) See the Note under Style.

   Old Testament. See Old Testament under Testament, and
      see tanak.

   Old wife. [In the senses
       b and
       c written also oldwife.]
       (a) A prating old woman; a gossip.

                 Refuse profane and old wives' fables. --1 Tim.
                                                  iv. 7.
       (b) (Zool.) The local name of various fishes, as the
           European black sea bream (Cantharus lineatus), the
           American alewife, etc.
       (c) (Zool.) A duck; the old squaw.

   Old World, the Eastern Hemisphere.
      [1913 Webster]

   Syn: Aged; ancient; pristine; primitive; antique; antiquated;
        old-fashioned; obsolete. See Ancient.
        [1913 Webster]

WordNet (r) 3.0 (2006):

old school
    n 1: a class of people favoring traditional ideas