Source : Webster's Revised Unabridged Dictionary (1913)

Restful \Rest"ful\ (r?st"f?l), a.
   1. Being at rest; quiet. --Shak.

   2. Giving rest; freeing from toil, trouble, etc.

            Tired with all these, for restful death I cry.
                                                  --Shak.
      -- {Rest"ful*ly}, adv. -- {Rest"ful*ness}, n.

Source : WordNet®

restful
     adj : affording or marked by rest or repose; "the time spent was
           pleasant and relaxing"; "a restful night"; "a cool and
           reposeful glen" [syn: {relaxing}, {reposeful}]