COLDER is a playable word

cold Scrabble® Dictionary

adjective
colder, coldest
having little or no warmth
noun
pl. colds
the relative lack of heat; a chill
62 Playable Words can be made from "COLDER"
   2-Letter Words (10 found)
   3-Letter Words (22 found)
   5-Letter Words (8 found)
   6-Letter Words (1 found)