Stories We Like: A Guide to the Comma
twitching of a facial muscle, 1822, often a shortening of tic douloureux "severe facial neuralgia," literally "painful twitch" (1800), from French tic "a twitching disease of horses" (early 17c.), of unknown origin. Klein suggests an imitative origin; French etymologists compare it to Italian ticchio "whim, caprice."
A habitual spasmodic muscular movement or contraction, usually of the face or extremities. Also called habit spasm.