twitch vs twitching

twitch and twitching both are nouns.

Word	Noun	Adjective	Verb	Adverb
twitch	Yes	No	Yes	No
twitching	Yes	No	No	No

As nouns, twitch and twitching are synonyms defined as:

twitch and twitching: a sudden muscle spasm; especially one caused by a nervous condition

Other synonyms of twitch include vellication.

twitch (noun)	twitching (noun)
a sudden muscle spasm; especially one caused by a nervous condition	a sudden muscle spasm; especially one caused by a nervous condition

twitch (verb)	twitching (verb)
make an uncontrolled, short, jerky motion
squeeze tightly between the fingers
move or pull with a sudden motion
toss with a sharp movement so as to cause to turn over in the air
move with abrupt, seemingly uncontrolled motions