LETTER is a playable word

letter Scrabble® Dictionary

verb
lettered, lettering, letters
to mark with letters (written symbols representing speech sounds)
24 Playable Words can be made from "LETTER"
   2-Letter Words (5 found)
   3-Letter Words (9 found)
   4-Letter Words (8 found)
   5-Letter Words (1 found)
   6-Letter Words (1 found)