HOBBYHORSE

noun Etymology: hobby small light horse, from Middle English hoby, hobyn, perhaps from Hobbin, nickname for Robert or Robin Date: circa 1553 1. a figure of a horse fastened about the waist in the morris dance, a dancer wearing this figure, buffoon , 3. a stick having an imitation horse's head at one end that a child pretends to ride, rocking horse , a toy horse suspended by springs from a frame, 4. a topic to which one constantly reverts, hobby II