FORMICATION
formication
(noun) hallucinated sensation that insects or snakes are crawling over the skin; a common side-effect of extensive use of cocaine or amphetamines
Source: WordNet® 3.1
Etymology
Noun
formication (countable and uncountable, plural formications)
(medicine) An abnormal skin sensation similar to that of insects crawling over or within the skin; a tactile hallucination involving such a sensation. A common side-effect of substance abuse, it can also be experienced with high fever, menopause, skin cancer, diabetic neuropathy, or herpes zoster.
Source: Wiktionary
For`mi*ca"tion, n. Etym: [L. formicatio, fr. formicare to creep like
an ant, to feel as if ants were crawling on one's self, fr. formica
ant: cf. F. formication.] (Med.)
Definition: A sensation resembling that made by the creeping of ants on the
skin. Dunglison.
Source: Webster’s Unabridged Dictionary 1913 Edition