muck
n.dirt, mud, or waste that is wet and sticky. You often use this word to describe something messy or gross, like animal waste on a farm.
n.moist, sticky matter such as mud, dirt, or animal excrement. Often carries a derogatory or informal tone when referring to general filth or low-quality substances.
“The dog came inside covered in muck from the garden.”
“After the heavy rain, the farmyard was a sea of muck that made walking nearly impossible.”
“The investigative report aimed to scrape away the muck of political corruption to reveal the systemic bribery occurring within the city council.”
Commonly used in the idiom 'muck in' (to help out) or 'muck up' (to ruin something).
“A resident in the area, who asked not to be named, told the BBC a muck spreader, which are normally used to distribute farmyard manure, had been used to spread medical waste.”
From Middle English mok, muk, from Old Norse myki, mykr (“dung”) or less likely Old English moc, moce (in hlōsmoc (“pigsty dung”) and lustmoce (“lady's smock (Cardamine pratensis)”)) (compare Icelandic mykja and Danish møg ("dung")), from Proto-Germanic mukį̄ (“dung; manure”), from Proto-Germanic muk-, from Proto-Indo-European (s)mewg-, mewk- (“slick, slippery”) (compare Welsh mign (“swamp”), Latin mūcus (“snot”), mucere (“to be moldy or musty”), Latvian mukls (“swampy”), Albanian myk (“mould”), Ancient Greek μύξα (múxa, “mucus, lamp wick”), Ancient Greek μύκης (múkēs, “mushroom”), German Mauke (“mud fever”)), from *(s)mewg, mewk 'to slip'. More at meek.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.