WordNet (r) 3.0 (2006):

bloodstain
    n 1: a discoloration caused by blood

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "bloodstain":
   bloody, blot, blotch, blur, brand, dab, daub, ensanguine, eyesore,
   fleck, flick, flyspeck, macula, maculation, macule, mark, patch,
   smear, smirch, smouch, smudge, smut, smutch, spatter, speck,
   speckle, splash, splatter, splotch, spot, stain, stigma, taint,
   tarnish