From WordNet (r) 3.0 (2006):
muck
n 1: any thick, viscous matter [syn: sludge, slime, goo,
goop, gook, guck, gunk, muck, ooze]
2: fecal matter of animals [syn: droppings, dung, muck]
v 1: remove muck, clear away muck, as in a mine
2: spread manure, as for fertilization [syn: manure, muck]
3: soil with mud, muck, or mire; "The child mucked up his shirt
while playing ball in the garden" [syn: mire, muck,
mud, muck up]