Noun. 1. numerousness - a large number. numerosity, multiplicity. number, figure - the property possessed by a sum or total or indefinite quantity of units or individuals; "he had a number of chores to do"; "the number of parameters is small"; "the figure was about a thousand"

What is called numerous?

adjective. very many; being or existing in great quantity: numerous visits; numerous fish. consisting of or comprising a great number of units or individuals: Recent audiences have been more numerous.

How do you explain numerous?

: consisting of great numbers of units or individuals born into a numerous family also : many received numerous complaints The people I'd like to thank are too numerous to mention.