Webster's Revised Unabridged Dictionary · 1913

Residuum

Residuum (-?m) , noun

[L. See Residue.]

That which is left after any process of separation or purification; that which remains after certain specified deductions are made; residue.
“I think so,” is the whole residuum... after evaporating the prodigious pretensions of the zealot demagogue. — L. Taylor