twiddle

Concise Oxford English Dictionary © 2008 Oxford University Press:
twiddle/ˈtwɪdl/

▶verb

• 1 play or fiddle with, typically in a purposeless or nervous way.

• 2 archaic turn or move in a twirling way.

▶noun

• 1 an act of twiddling.

• 2 a rapid or intricate series of musical notes.

– phrases
twiddle one's thumbs have nothing to do.

– derivatives
twiddler noun,
twiddly adjective.

– origin C16 (in the sense ‘trifle’): appar. imitative, combining twirl or twist with fiddle.