twitch

Short definition from Wiktionary

Noun

1. 1
   A brief, small (sometimes involuntary) movement out of place and then back again; a spasm.
2. 2
   Action of spotting or seeking out a bird, especially a rare one.
3. 3
   A stick with a hole in one end through which passes a loop, which can be drawn tightly over the upper lip or an ear of a horse and twisted to keep the animal quiet during minor surgery.
4. 4
   A brief, contractile response of a skeletal muscle elicited by a single maximal volley of impulses in the neurons supplying it.
5. 5
   The sudden narrowing almost to nothing of a vein of ore.
6. 6
   A trip taken in order to observe a rare bird.
7. 7
   couch grass (Elymus repens; a species of grass, often considered as a weed)

Verb

1. 1
   To perform a twitch; spasm.
2. 2
   To cause to twitch; spasm.
3. 3
   To jerk sharply and briefly.
4. 4
   To exert oneself.
5. 5
   To spot or seek out a bird, especially a rare one.

Proper noun

1. 1
   A live streaming service that focuses on video game live streaming.