sludge

1 ENTRIES FOUND:
sludge /ˈslʌʤ/ noun
sludge
/ˈslʌʤ/
noun
Britannica Dictionary definition of SLUDGE
[noncount]
1 
: thick, soft, wet mud
2 
: a soft, thick material that is produced in various industrial processes (such as in the treatment of sewage)
3 
: a thick material that can form in the oil in an engine and cause engine problems

— sludgy

/ˈslʌʤi/ adjective sludgier; sludgiest