Other forms: squirming, squirmed, squirms
To squirm is to wriggle about, usually from discomfort. Squirm in the seat, made him squirm, squirming with embarrassment.
The discomfort is the point — squirming is what a body does when it wants to be somewhere else. Make somebody squirm means to embarrass them deliberately and watch. Physically it describes children in chairs and anything worm-like. Note that the word was first used of eels in the 1690s, which is exactly the right image, and that its origin beyond that is unknown.
1verbsquirmTo wriggle about, usually from discomfort.
“The little boy squirmed in his chair all through the long sermon.”
squirm is a wriggling.
The word is first recorded in the 1690s, originally of eels, and its origin is unknown. It may be imitative or related to Scots squimmer.
First recorded 1690's, originally used of eels; cognate with Scots squimmer (“to wriggle, squirm”). Of unknown origin. Compare dialectal quirm, whirm (“to disappear quickly, vanish suddenly and mysteriously”), Norwegian kverva (“to turn around, take away, remove, shrink”), from Old Norse hverfa (“to turn, vanish”). Alternatively, perhaps imitative of the sound or related to worm (in the sense of writhing movement) or swarm.
Etymology from Wiktionary, CC BY-SA