Source : Webster's Revised Unabridged Dictionary (1913)

Numerosity \Nu`mer*os"i*ty\, n. [L. numerositas.]
   1. The state of being numerous; numerousness. [Obs.]

   2. Rhythm; harmony; flow. [Obs.]

            The numerosity of the sentence pleased the ear. --S.
                                                  Parr.

Source : WordNet®

numerosity
     n : a large number [syn: {numerousness}, {multiplicity}]