1. The substance left after distilling off all but the heaviest components from crude oil in petroleum refinery operations. Also known as bottoms; residuum.

2. Solids deposited onto the filter medium during filtration. Also known as cake; discharged solids.

The in-place accumulation of rock debris which remains after weathering has removed all but the least soluble constituent.

1. The residue of a complex function f (z ) at an isolated singularity z₀ is given by (1/2πi ) ∫ f (z )dz along a simple closed curve interior to an annulus about z₀; equivalently, the coefficient of the term (z - z₀)^-1 in the Laurent series expansion of f (z ) about z₀.

2. In general, a coset of an ideal in a ring.

3. A residue of m of order n, where m and n are integers, is a remainder that results from raising some integer to the nth power and dividing by m.