Source : Webster's Revised Unabridged Dictionary (1913)

Bachelor \Bach"e*lor\ (b[a^]ch"[-e]*l[~e]r), n. [OF. bacheler
   young man, F. bachelier (cf.Pr. bacalar, Sp. bachiller, Pg.
   bacharel, It. baccalare), LL. baccalarius the tenant of a
   kind of farm called baccalaria, a soldier not old or rich
   enough to lead his retainers into battle with a banner, a
   person of an inferior academical degree aspiring to a
   doctorate. In the latter sense, it was afterward changed to
   baccalaureus. See {Baccalaureate}, n.]
   1. A man of any age who has not been married.

            As merry and mellow an old bachelor as ever followed
            a hound.                              --W. Irving.

   2. An unmarried woman. [Obs.] --B. Jonson.

Source : WordNet®

bachelor
     n 1: a man who has never been married [syn: {unmarried man}]
     2: a knight of the lowest order; could display only a pennon
        [syn: {knight bachelor}, {bachelor-at-arms}]

bachelor
     v : lead a bachelor's existence [syn: {bach}]