CARDIOID is a playable word

cardioid Scrabble® Dictionary

noun
pl. cardioids
a heart-shaped curve
70 Playable Words can be made from "CARDIOID"
   2-Letter Words (9 found)
   3-Letter Words (26 found)
   5-Letter Words (11 found)
   6-Letter Words (2 found)
   8-Letter Words (1 found)