Home › Words › O › onychotillomaniaonychotillomaniaonychotillomania · noun — A compulsion for picking and tearing at one's fingernails or toenails.Definition from Wiktionary (CC BY-SA 3.0).EtymologyFrom Ancient Greek ὄνυξ (ónux, “nail”) (compare onycho-) + τίλλω (tíllō, “to pluck”) + -mania.nounA compulsion for picking and tearing at one's fingernails or toenails.Definitions & examples from Wiktionary (CC BY-SA 3.0).