Source : Webster's Revised Unabridged Dictionary (1913)

Amateurish \Am`a*teur"ish\, a.
   In the style of an amateur; superficial or defective like the
   work of an amateur. -- {Am`a*teur"ish*ly}, adv. --
   {Am`a*teur"ish*ness}, n.

Source : WordNet®

amateurish
     adj : lacking professional skill or expertise; "a very amateurish
           job"; "inexpert but conscientious efforts"; "an
           unskilled painting" [syn: {amateur}, {inexpert}, {unskilled}]