'Formication' definitions:

Definition of 'formication'

From: WordNet
noun
Hallucinated sensation that insects or snakes are crawling over the skin; a common side-effect of extensive use of cocaine or amphetamines

Definition of 'Formication'

From: GCIDE
  • Formication \For`mi*ca"tion\, n. [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.) A sensation resembling that made by the creeping of ants on the skin. --Dunglison. [1913 Webster]