SWIFTEST is a playable word

swift Scrabble® Dictionary

adjective
swifter, swiftest
moving with a great rate of motion
noun
pl. swifts
a fast-flying bird
95 Playable Words can be made from "SWIFTEST"
   2-Letter Words (12 found)
   3-Letter Words (25 found)
   6-Letter Words (5 found)
   8-Letter Words (1 found)