RAPIDEST is a playable word

rapid Scrabble® Dictionary

adjective
rapider, rapidest
fast-moving
(adverb) rapidly
noun
pl. rapids
a fast-moving part of a river
502 Playable Words can be made from "RAPIDEST"
   2-Letter Words (23 found)
   3-Letter Words (82 found)
   8-Letter Words (2 found)