Source : Webster's Revised Unabridged Dictionary (1913)

Minuend \Min"u*end\, n. [L. minuendus to be diminished, fr.
   minuere to lessen, diminish. See {Minish}.] (Arith.)
   The number from which another number is to be subtracted.

Source : WordNet®

minuend
     n : the number from which the subtrahend is subtracted