FLATTEN is a playable word

flatten Scrabble® Dictionary

verb
flattened, flattening, flattens
to make or become flat
79 Playable Words can be made from "FLATTEN"
   2-Letter Words (15 found)
   3-Letter Words (27 found)
   5-Letter Words (4 found)
   6-Letter Words (4 found)
   7-Letter Words (1 found)