The term 'curmudgeonly sort' is used to describe someone who is grumpy, irritable, and generally unpleasant. The crossword solutions for this term are 'HATER' (5 letters) and 'CRAB' (4 letters). Both words refer to a person's negative attitude and behavior, with 'HATER' referring to someone who is hostile and resentful towards others, and 'CRAB' referring to someone who is easily irritated and quick to complain.