These words refer to convulsed or contorted movements within a body. Wriggle can suggest a deliberate shaking or shuddering not intended to result in motion along a path: wriggling uncomfortably in his wet clothes; wriggling with delight as the waves broke over her. More often, the word does suggest forward movement achieved by a crawling or creeping action: wriggling into the tunnel with a torch in one hand; a caterpillar that wriggled down the girl’s back. Slither points exclusively to this sort of movement, but, whereas wriggle may suggest jerking, awkward or ungainly motion, slither implies a sinuous and graceful sliding of an elongated body, such as that of a snake: pythons slithering noiselessly over a rock; a rope that slithered unseen down the prison wall.

Squirm is nearly identical to wriggle in suggesting either in-place shaking or a forward crawl. In both cases, a greater amount of internal undulation is suggested by squirm , as well as more thrashing about: watching the stranded octopus squirm each time they stabbed at it; trying desperately to squirm free from the tangled bedclothes. In contrast to the foregoing words, both writhe and wiggle point primarily to in-place motion. Writhe would suggest a slower, less voluntary shuddering than squirm and even wriggle ; it often describes the throes of someone in pain: bodies writhing in agony. But the word can suggest other kinds of contorted movement as well: writhing teenagers dancing the frug. Wiggle suggests a side-to-side or back-and-forth motion: proving to them that he could wiggle his ears; the woman who seemed unaware of how much she wiggled as she walked. As in the last example, if forward movement is indicated, the word points to incidental motion rather than to motion that contributes directly to the gaining of ground.