(intransitive) To perform a twitch; spasm. / (transitive) To cause to twitch; spasm. / (transitive) To jerk sharply and briefly. / (obsolete) To exert oneself.

A brief, small (sometimes involuntary) movement out of place and then back again; a spasm. / (informal) Action of spotting or seeking out a bird, especially a rare one.

couch grass (Elymus repens; a species of grass, often considered as a weed)

plural of twitching

simple past tense and past participle of twitch

That twitches.

Someone or something that twitches. / An eager birdwatcher who is willing to travel long distances to see rare species. (See the Wikipedia article for origin.)

present participle of twitch

The motion of something that twitches. / (birdwatching) Compulsive birdwatching by people (twitchers) who travel long distances to see rare species.

The state of being twitchy, physical restlessness. / The state of being nervous and unsettled; edginess.