60 connections / rhymes. 144 Sludge Sludge Definition: Sludge refers to the residual, semi-solid material left from industrial wastewater, or sewage treatment processes.. Wikipedia suggests Sludge . Sludge contains 6 letters and has 144 connections / rhymes. 109 Smudge Smudge Definition: Smudge is an Australian indie / country-rock / power-pop band..