Caterpillar

1. the larva of a butterfly or moth, which has a segmented wormlike body with three pairs of true legs and several pairs of appendages similar to legs.
2. an articulated steel band passing round the wheels of a vehicle for travel on rough ground.

late Middle English: perhaps from a variant of Old French chatepelose, literally ‘hairy cat’, influenced by obsolete piller ‘ravager’. The association with ‘cat’ is found in other languages, e.g. Swiss German Teufelskatz (literally ‘devil's cat’), Lombard gatta (literally ‘cat’). Compare with French chaton, English catkin, which resembles a hairy caterpillar.