caterpillar [LME] The caterpillar first appeared in English in the form catyrpel, probably an alteration of the Old French word chatepelose, literally ‘hairy cat’. English used to have a word piller, meaning ‘a plunderer or ravager’ (related to pillage) and, given the damage that caterpillars do to plants, it is likely that this influenced how the word is spelt.