The term RELATIVE OF A RABBIT can be solved by two four-letter words: PIKA and HARE. A pika is a small mammal that is closely related to rabbits and hares, and is often referred to as a 'rock rabbit' or 'boulder bunny'. Hares are also closely related to rabbits, but are generally larger and have longer ears and legs. Both animals are members of the Leporidae family, which includes rabbits, hares, and pikas.