"morbid fear of cats," 1905, with -phobia "fear" + Greek ailouros "cat" (probably only "wildcat," as "domestic cats were not found in the Greek world" [Beekes]), which is of unknown origin. Usually explained as a compound of aiolos "quick-moving" + oura "tail," hence "with moving tail," which is plausible despite some phonetic difficulties, according to Beekes, who also notes "the word may well have been adapted by folk etymology ...." Related: Ailurophobe (1914).