Definition of sludges:
(n) :
A residual semi-solid material left from industrial, water treatment, or wastewater treatment processes.
(n) :
Solids separated from suspension in a liquid.
(n) :
A sediment of accumulated minerals in a steam boiler.
(n) :
A mass of small pieces of ice on the surface of a water body.
(n) :
(behavioral science) Institutional policies that introduce tedium and inefficiency in processes.
(v) :
(intransitive, informal) To slump or slouch.