n. & v.
n. 1 farmyard manure. 2 colloq. dirt or filth; anything disgusting. 3 colloq. an untidy state; a mess.
v.tr. 1 (usu. foll. by up) Brit. colloq. bungle (a job). 2 (foll. by out) remove muck from. 3 make dirty. 4 manure with muck. make a muck of colloq. bungle. muck about (or around) Brit. colloq. 1 potter or fool about. 2 (foll. by with) fool or interfere with. muck in Brit. (often foll. by with) share tasks etc. equally. muck sweat Brit. colloq. a profuse sweat.
[ ME muk prob. f. Scand.: cf. ON myki dung, rel. to MEEK ]