To move in a twisting or contorted motion, (especially when struggling):
— The prisoner writhed in discomfort.

synonyms: squirm, twist, worm, wrestle, wriggle.

Roget 243: distort, contort, twist, warp, wrest, writhe, make faces, deform, misshape.   

Roget 315: be agitated &c.; shake; tremble, tremble like an aspen leaf; quiver, quaver, quake, shiver, twitter, twire^†, writhe, toss, shuffle, tumble, stagger, bob, reel, sway, wag, waggle; wriggle, wriggle like an eel; dance, stumble, shamble, flounder, totter, flounce, flop, curvet, prance, cavort [U.S.]; squirm.    throb, pulsate, beat, palpitate, go pitapat; flutter, flitter, flicker, bicker; bustle.    ferment, effervesce, foam; boil, boil over; bubble up; simmer.    toss about, jump about; jump like a parched pea; shake like an aspen leaf; shake to its center, shake to its foundations; be the sport of the winds and waves; reel to and fro like a drunken man; move from post to pillar and from pillar to move from post to pillar and from pillar to post, drive from post to pillar and from pillar to drive from post to pillar and from pillar to post, keep between hawk and buzzard.    agitate, shake, convulse, toss, tumble, bandy, wield, brandish, flap, flourish, whisk, jerk, hitch, jolt; jog, joggle, jostle, buffet, hustle, disturb, stir, shake up, churn, jounce, wallop, whip, vellicate^†.    ... show more

Roget 378: feel pain, experience pain, suffer pain, undergo pain etc. n.; suffer, ache, smart, bleed; tingle, shoot; twinge, twitch, lancinate^†; writhe, wince, make a wry face; sit on thorns, sit on pins and needles.    give pain, inflict pain; lacerate; pain, hurt, chafe, sting, bite, gnaw, gripe; pinch, tweak; grate, gall, fret, prick, pierce, wring, convulse; torment, torture; rack, agonize; crucify; cruciate^†, excruciate^†; break on the wheel, put to the rack; flog etc. (punish) 972; grate on the ear etc. (harsh sound) 410.    ... show more

Dutch: spartelen, vervormen, draaien, kronkelen, ontwijken, wiebelen, wriemelen, wringen