Etymology: Catyrpel , in Promp. Parv., may be merely an error of the scribe for catyrpelour (or -er ); Palsgrave has the full form. Generally compared with the synonymous Old French chatepelose , lit. ‘hairy or downy cat’ (compare the Scots name hairy woubit ‘woolly bear’), of which the Old Northern French would be catepelose . This is a possible source, though no connection is historically established: the final sibilant might be treated in English as a plural formative, and the supposed singular catepelo would be readily associated with the well-known word piller , pilour , pillager, plunderer, spoiler. This is illustrated by the fact that in the figurative sense, piller and caterpiller are used synonymously in a large number of parallel passages (see sense 2). The regular earlier spelling was with -er; the corruption caterpillar (? after pillar), occasional in 17th cent., was adopted by Johnson, and has since prevailed. (Some think the word a direct compound of piller. The giving to hairy caterpillars a name derived from the cat, is seen not only in the French word cited, but also in Lombard gatta, gattola (cat, kitten), Swiss teufelskatz (devil's cat); compare also French chenille ( < canicula little dog), Milanese can, cagnon (dog, pup) a silk-worm (Wedgwood). Compare also catkin, French chaton, applied to things resembling hairy caterpillars.)

Etymology: < caterpillar n.Previous versions of the OED give the stress as: ˈcaterpillar.