WordNet (r) 3.0 (2006):

goop
    n 1: any thick, viscous matter [syn: sludge, slime, goo,
         goop, gook, guck, gunk, muck, ooze]
    2: street names for gamma hydroxybutyrate [syn: soap, scoop,
       max, liquid ecstasy, grievous bodily harm, goop,
       Georgia home boy, easy lay]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "goop":
   albumen, batter, bonnyclabber, butter, clabber, cornstarch, cream,
   curd, dough, egg white, gaum, gel, gelatin, glair, glop, glue,
   gluten, goo, gook, gruel, gumbo, gunk, jam, jell, jelly, loblolly,
   molasses, mucilage, muck, mucus, pap, paste, porridge, pudding,
   pulp, puree, putty, rob, semifluid, semiliquid, size, soup, starch,
   sticky mess, syrup, treacle