noun

1. a narrow strip of leather, etc. used as a lace, strap, etc.
2. a whiplash, as of plaited strips of hide
3. a kind of sandal consisting usually of a flat rubber sole held on the foot by a strap slipped between the big toe and the toe next to it
4. 1. a kind of bikini swimsuit bottom having only a narrow strip of fabric that goes between the legs and attaches in back to a waistband, so as to show the buttocks
      also thong bikini
   2. a pair of brief underpants like this

Etymology: ME < OE thwang, twisted string, thong: see twinge