THUMB is a playable word

thumb Scrabble® Dictionary

verb
thumbed, thumbing, thumbs
to leaf through with the thumb (the short, thick digit of the human hand)
15 Playable Words can be made from "THUMB"
   2-Letter Words (5 found)
   3-Letter Words (8 found)
   4-Letter Words (1 found)
   5-Letter Words (1 found)