To twist or twine something lightly and repeatedly, often while thinking or bored; to make small adjustments.
Possibly from 'twill' or related to 'twine.' The word appears in English in the 17th century with unclear origins, possibly from East Anglian dialect. The repetitive motion it describes—turning something slowly—matches its sound.
'Twiddle your thumbs' is the perfect phrase because thumbs are the only fingers you can actually twiddle easily, and the phrase perfectly captures the anxiety of waiting helplessly. It's so universally understood that people do it in every culture, even if they don't use that exact word!
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