WordNet (r) 3.0 (2006):

screw up
    v 1: make more intense; "Emotions were screwed up" [syn: heat
         up, hot up, screw up]
    2: make a mess of, destroy or ruin; "I botched the dinner and we
       had to eat out"; "the pianist screwed up the difficult
       passage in the second movement" [syn: botch, bodge,
       bumble, fumble, botch up, muff, blow, flub,
       screw up, ball up, spoil, muck up, bungle, fluff,
       bollix, bollix up, bollocks, bollocks up, bobble,
       mishandle, louse up, foul up, mess up, fuck up]
    3: screw or turn higher
    4: twist into a strained configuration; "screw up one's face"

Moby Thesaurus II by Grady Ward, 1.0:

129 Moby Thesaurus words for "screw up":
   abreast, acquainted, affix, amiss, anarchy, anchor, annex, attach,
   au courant, back, ball up, belay, bitch, bitch up, bloomer,
   blooper, blow, bobble, bollix, bollix up, bonehead into it,
   bonehead play, boner, boo-boo, boob stunt, boot, brace, bugger,
   bugger up, bum, bungle, cement, chaos, cinch, clamp, clinch,
   complicate, confound, confuse, confusion, cook, cramp, crappy,
   dissatisfactory, drop a brick, drop the ball, duff, dumb trick,
   embrangle, engraft, entangle, fabulous formless darkness, fasten,
   fix, flub, fluff, fool mistake, foozle, foul up, foul-up, fumble,
   garble, goof, goof up, graft, grapple, gum up, hash up, hassle,
   howler, implicate, involve, jumble, knit, knot, license, louse up,
   louse-up, make fast, mess, mess up, misrule, mix up, mix-up, moor,
   morass, muck up, muck-up, muddle, muff, perplex, pi,
   play hell with, play hob with, poor, pratfall, pull a boner, punk,
   put to, queer, ramify, ravel, reinforce, riffle, rigidify, rotten,
   scramble, screamer, secure, set, set to, shore up, shuffle, sink,
   snafu, snarl, snarl up, spoil, stiffen, strengthen, tangle, tense,
   tighten, trice up, trim, tumble, unsatisfactory, up-to-the-minute,
   wrong