Source : Webster's Revised Unabridged Dictionary (1913)

Helpful \Help"ful\, a.
   Furnishing help; giving aid; assistant; useful; salutary.

         Heavens make our presence and our practices Pleasant
         and helpful to him!                      --Shak.
   -- {Help"ful*ly}, adv. -- {Help"ful*ness}, n. --Milton.

Source : WordNet®

helpful
     adj 1: providing assistance or serving a useful function [ant: {unhelpful}]
     2: of service or assistance; "a child who is helpful around the
        house can save the mother many steps"
     3: showing a willingness to cooperate; "a helpful cooperative
        patient"; "parents hope to raise children who are
        considerate and helpful to others"