Mucking down a sloppy joe right now text me later. One side has the word, one side has the definition. walking (aka mucking) through a big muddy area. A moist sticky mixture, especially of mud and filth. 2. Moist farmyard dung; manure. 3. Dark fertile soil containing decaying vegetable matter. 4. Something filthy or. muck in meaning, definition, what is muck in: to share the work that needs to be done. Learn more.