an abnormal fear of clowns.

Origin of coulrophobia

1980-85; coulro- (perhaps < Greek kolon limb; with sense of 'stilt-walker', hence 'clown') + -phobia
Related formscoul·ro·pho·bic, adjective, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Word Origin and History for coulrophobia

"morbid fear of clowns," by 2001 (said in Web sites to date from 1990s or even 1980s), a popular term, not from psychology, possibly facetious, though the phenomenon is real enough; said to be built from Greek kolon "limb," with some supposed sense of "stilt-walker," hence "clown" + -phobia.

Ancient Greek words for "clown" were sklêro-paiktês, from paizein "to play (like a child);" or deikeliktas; other classical words used for theatrical clowns were related to "rustic," "peasant" (cf. Latin fossor "clown," literally "laborer, digger," related to fossil).

The whole creation looks suspiciously like the sort of thing idle pseudo-intellectuals invent on the Internet and which every smarty-pants takes up thereafter; perhaps it is a mangling of Modern Greek klooun "clown," which is the English word borrowed into Greek.

Online Etymology Dictionary, © 2010 Douglas Harper