muck

American  

[muhk] / mʌk /

noun

1. moist farmyard dung, decaying vegetable matter, etc.; manure.

2. a highly organic, dark or black soil, less than 50 percent combustible, often used as a manure.

3. mire; mud.

4. filth, dirt, or slime.

5. defamatory or sullying remarks.

6. a state of chaos or confusion.

   to make a muck of things.

7. Chiefly British Informal. something of no value; trash.

8. (especially in mining) earth, rock, or other useless matter to be removed in order to get out the mineral or other substances sought.

---

verb (used with object)

1. to manure.

2. to make dirty; soil.

3. to remove muck from (sometimes followed byout ).

4. Informal.

   1. to ruin; bungle (often followed byup ).

   2. to put into a state of complete confusion (often followed byup ).

verb phrase

1. muck about / around to idle; waste time; loiter.

muck British  

/ mʌk /

noun

1. farmyard dung or decaying vegetable matter

2. Also called: muck soil.  an organic soil rich in humus and used as a fertilizer

3. dirt or filth

4. earth, rock material, etc, removed during mining excavations

5. slang rubbish

6. See Lord Muck Lady Muck

7. slang to ruin or spoil

---

verb

1. to spread manure upon (fields, gardens, etc)

2. to soil or pollute

3. (often foll by out) to clear muck from

Etymology

Origin of muck

1200–50; Middle English muc, muk < Old Norse myki cow dung

Explanation

Muck is a goopy, muddy substance, like the muck at the bottom of a pond or the muck you clean out of the gutters on your house once a year. You can also use muck to mean animal manure, its original, 13th-century meaning — specifically, "cow dung and vegetable matter used as manure." The definition has expanded since then to include any number of dirty, slimy substances, from the mud on the bottom of a lake to the sludge in a flooded basement. As a verb, to muck is either to remove animal waste or to spread manure on a field.

Example Sentences

A woman, in a rhinestone shirt, told me that she wanted to convene her fellow cyclists to whizz by the gulleys and alleyways around Tucson, searching for clues in the muck.

From Slate • Feb. 23, 2026

Laura Stacey’s quote flags Canada’s strategy: muck it up.

From The Wall Street Journal • Feb. 17, 2026

“Like slime, sludge, and muck, slop has the wet sound of something you don’t want to touch,” the editors continued.

From Salon • Jan. 13, 2026

Making gas out of cow muck is widely agreed to be a win for the planet.

From BBC • Dec. 17, 2025

Water and muck and Spackle skin worked fine together, didn’t poison nothing, just made the swamp richer, like men do to soil.

From "The Knife of Never Letting Go" by Patrick Ness

Related Words

• dirt
• goo
• gunk
• manure
• mud
• slime
• sludge
• trash