Answer: SURLIEST

AnswerCrossword Clue
SURLIESTMost grumpy
SURLIESTMost bad-tempered
SURLIESTMost irascible
SURLIESTMost churlish.
SURLIESTWorst-tempered
SURLIESTLeast potite
surliestSURLY, sullenly rude
surliestrude and sullen