STIMULI is a playable word

stimulus Scrabble® Dictionary

noun
pl. stimuli
something that causes a response
60 Playable Words can be made from "STIMULI"
   2-Letter Words (10 found)
   3-Letter Words (18 found)
   5-Letter Words (5 found)
   6-Letter Words (3 found)
   7-Letter Words (1 found)