twitching

Short definition from Wiktionary

Verb

1. 1
   present participle and gerund of twitch

Noun

1. 1
   The motion of something that twitches.
2. 2
   Compulsive birdwatching by people (twitchers) who travel long distances to see rare species.
3. 3
   Using a horse team to pull logs.

Adjective

1. 1
   That twitches.