Complain to is a term used to describe the act of expressing dissatisfaction or annoyance. GRIPE, CARP, GROUSE, RAIL, and NAG are all synonyms for complain to. GRIPE is a five-letter word meaning to express dissatisfaction or annoyance in a peevish or petulant manner. CARP is a four-letter word meaning to find fault or complain querulously or unreasonably. GROUSE is a six-letter word meaning to complain or grumble. RAIL is a four-letter word meaning to scold or complain in an angry or bitter manner. Finally, NAG is a three-letter word meaning to annoy or irritate by constant scolding, complaining, or urging.