1 fouled, befouled, muddied, mud-spattered, dirty, grubby, grimy, soiled, mud-caked, slimy, mucky, miry; oozy, squelchy, squashy, boggy, fenny, marshy, swampy; Formal feculent; Colloq squishy, squushy:
Take off those muddy boots before you come into the house. The walk up to the house has become all muddy in the rain
2 confused, unclear, vague, obscure, dull, dim, fuzzy, muddled, addled, mixed-up:
Greg has only a muddy idea of what you're talking about.
3 drab, subdued, blurred, dingy, flat, murky, mat, washed out:
The colours in her paintings look very muddy to me.
4 obscure, dull, dim, confuse, mix up, befog, cloud:
His explanation muddied the issue rather than clarifying it.
5 dirty, soil, begrime, smirch, besmirch, spatter, bespatter:
A passing car muddied my new skirt.