BUG BACK is a term that can be used to describe a situation in which a person or group of people are dealing with a problem that keeps coming back. The crossword solutions for this term are ANT (3 letters), FLU (3 letters), and REPEL (5 letters). ANT is an abbreviation for an insect, which is often seen as a symbol of something that is persistent and hard to get rid of. FLU is an abbreviation for influenza, which is a virus that can cause recurring illnesses. REPEL is a verb meaning to drive away or keep away, which can be used to describe the action of trying to prevent a problem from returning.