fuzzy set

noun Mathematics.
  1. a generalization of a classical set with the property that each member of a population of objects has associated with it a number, usually from 0 to 1, that indicates the degree to which the object belongs to the set.

Origin of fuzzy set

First recorded in 1960–65
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018