Source : Webster's Revised Unabridged Dictionary (1913)

Assistant \As*sist"ant\, a. [Cf. F. assistant, p. pr. of
   assister.]
   1. Helping; lending aid or support; auxiliary.

            Genius and learning . . . are mutually and greatly
            assistant to each other.              --Beattie.

   2. (Mil.) Of the second grade in the staff of the army; as,
      an assistant surgeon. [U.S.]

   Note: In the English army it designates the third grade in
         any particular branch of the staff. --Farrow.

Assistant \As*sist"ant\, n.
   1. One who, or that which, assists; a helper; an auxiliary; a
      means of help.

            Four assistants who his labor share.  --Pope.

            Rhymes merely as assistants to memory. --Mrs.
                                                  Chapone.

   2. An attendant; one who is present. --Dryden.

Source : WordNet®

assistant
     adj : of or relating to a person who is subordinate to another
           [syn: {adjunct}]

assistant
     n : a person who contributes to the fulfillment of a need or
         furtherance of an effort or purpose; "my invaluable
         assistant"; "they hired additional help to finish the
         work" [syn: {helper}, {help}, {supporter}]