Source : Webster's Revised Unabridged Dictionary (1913)

Waif \Waif\, n. [OF. waif, gaif, as adj., lost, unclaimed, chose
   gaive a waif, LL. wayfium, res vaivae; of Scand. origin. See
   {Waive}.]
   1. (Eng. Law.) Goods found of which the owner is not known;
      originally, such goods as a pursued thief threw away to
      prevent being apprehended, which belonged to the king
      unless the owner made pursuit of the felon, took him, and
      brought him to justice. --Blackstone.

   2. Hence, anything found, or without an owner; that which
      comes along, as it were, by chance. ``Rolling in his mind
      old waifs of rhyme.'' --Tennyson.

   3. A wanderer; a castaway; a stray; a homeless child.

            A waif Desirous to return, and not received.
                                                  --Cowper.

Source : WordNet®

waif
     n : a homeless child especially one forsaken or orphaned;
         "street children beg or steal in order to survive" [syn:
         {street child}]