Definition from Wiktionary, the free dictionary
- (uncountable, informal) dirt or grime; any vague or unknown substance
- I washed all the gunk off the light fixture, and found that it was white, not brown.
- (uncountable) A subculture of 21st century American males, combining elements of modern gothic culture with punk rock.
- (countable) A member of the gunk subculture.
Derived terms 
dirt or grime; any vague or unknown substance