[1] : The Collaborative International Dictionary of English v.0.48

residuum \resid"uum\ -?m, n. l. see residue.
   that which is left after any process of separation or
   purification; that which remains after certain specified
   deductions are made; residue.
   1913 webster

         "i think so," is the whole residuum . . . after
         evaporating the prodigious pretensions of the zealot
         demagogue.                               --l. taylor.
   1913 webster
see also:
residue 

[2] : WordNet (r) 2.0

residuum
     n : something left after other parts have been taken away;
         "there was no remainder"; "he threw away the rest"; "he
         took what he wanted and i got the balance" syn: remainder,
          balance, residual, residue, rest
     also: residua pl
see also:
remainder balance residual residue rest residua 

Residuum >> R Words
Residuum, definition of term: Residuum
residuum_pag1.html