WordNet (r) 3.0 (2006):

stand fast
    v 1: refuse to abandon one's opinion or belief [syn: stand
         pat, stand firm, hold firm, stand fast]

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "stand fast":
   abide, be still, be unflappable, coast, die hard, dig in, freeze,
   get home free, hang in, hang in there, hang tough, hold fast,
   hold out, hold up, keep quiet, lie still, mark time, never say die,
   not back down, not breathe, not budge, not give up, not stir,
   not submit, remain, remain firm, remain motionless, repose, rest,
   ride it out, stand, stand firm, stand no nonsense, stand pat,
   stand still, stand the gaff, stay, stay it out, stay put, stick,
   stick fast, stick it out, take what comes, tarry, tread water,
   weather, weather the storm