muck

Concise Oxford English Dictionary © 2008 Oxford University Press:
muck/mʌk/

▶noun

• 1 dirt or mud.

  ■ informal something unpleasant or worthless.

• 2 manure.

▶verb

• 1 (muck something up) informal spoil something.

  ■ (muck about/around with something) spoil something by interfering with it.

• 2 (muck something out) chiefly Brit. remove manure and other dirt from a stable etc.

• 3 (muck about/around) Brit. informal behave in a silly or aimless way.

• 4 (muck someone about/around) Brit. informal treat someone inconsiderately, typically by disrupting their plans.

• 5 (muck in) Brit. informal share tasks or accommodation.

– phrases
Lord (or Lady) Muck Brit. informal a socially pretentious man (or woman).

– origin ME muk, prob. of Scand. origin: cf. ON myki ‘dung’, from a Gmc base meaning ‘soft’, shared by meek.