Source : Webster's Revised Unabridged Dictionary (1913)

Groom \Groom\, n. [Cf. Scot. grome, groyme, grume, gome, guym,
   man, lover, OD. grom boy, youth; perh. the r is an insertion
   as in E. bridegroom, and the word is the same as AS. guma
   man. See {Bridegroom}.]
   1. A boy or young man; a waiter; a servant; especially, a man
      or boy who has charge of horses, or the stable. --Spenser.

   2. One of several officers of the English royal household,
      chiefly in the lord chamberlain's department; as, the
      groom of the chamber; the groom of the stole.

   3. A man recently married, or about to be married; a
      bridegroom. --Dryden.

   {Groom porter}, formerly an officer in the English royal
      household, who attended to the furnishing of the king's
      lodgings and had certain privileges.

Groom \Groom\, v. i. [imp. & p. p. {Groomed}; p. pr. & vb. n.
   {Grooming}.]
   To tend or care for, or to curry or clean, as a, horse.

Source : WordNet®

groom
     n 1: a man participant in his own marriage ceremony [syn: {bridegroom}]
     2: someone employed in a stable to take care of the horses
        [syn: {stableman}, {stableboy}, {hostler}, {ostler}]
     3: a man who has recently been married [syn: {bridegroom}]

groom
     v 1: prepare (someone) for a future role or function; "He is
          grooming his son to become his successor"; "The prince
          was prepared to become King one day"; "They trained him
          to be a warrior" [syn: {prepare}, {train}]
     2: give a neat appearance to; "groom the dogs"; "dress the
        horses" [syn: {dress}, {curry}]
     3: care for one's external appearance; "He is always
        well-groomed" [syn: {neaten}]