thrash
     n : a swimming kick used while treading water
     v 1: give a thrashing to; beat hard [syn: {thresh}, {lam}, {flail}]
     2: move or stir about violently; "The feverish patient thrashed
        around in his bed" [syn: {convulse}, {thresh}, {thresh
        about}, {thrash about}, {slash}, {toss}, {jactitate}]
     3: dance the slam dance [syn: {slam dance}, {slam}, {mosh}]
     4: beat so fast that (the heart's) output starts dropping until
        (it) does not manage to pump out blood at all
     5: move data into and out of core rather than performing useful
        computation; "The system is thrashing again!"
     6: beat the seeds out of a grain [syn: {thresh}]
     7: beat thoroughly in a competition or fight; "We licked the
        other team on Sunday!" [syn: {bat}, {clobber}, {drub}, {lick}]
Source: WordNet® 2.0

thrash vi. To move wildly or violently, without accomplishing anything
   useful. Paging or swapping systems that are overloaded waste most of
   their time moving data into and out of core (rather than performing
   useful computation) and are therefore said to thrash. Someone who keeps
   changing his mind (esp. about what to work on next) is said to be
   thrashing. A person frantically trying to execute too many tasks at once
   (and not spending enough time on any single task) may also be described
   as thrashing. Compare {multitask}.


Source: The Jargon File