jitters

Concise Oxford English Dictionary © 2008 Oxford University Press:
jitter /ˈʤɪtə/ informal

▶noun

• 1 (the jitters) a feeling of extreme nervousness.

• 2 slight, irregular movement, variation, or unsteadiness in an electrical signal or electronic device.

▶verb

• 1 act nervously.

• 2 (of a signal or device) suffer from jitter.

– derivatives
jitteriness noun,
jittery adjective.

– origin 1920s: of unknown origin.