fuzzy set
noun
: a mathematical set with the property that an object can be a member of the set, not a member of the set, or any of a continuum of states of being a partial member of the set
Example Sentences
Recent Examples on the Web Based on the reviews of Amazon shoppers, Williams isn't the only one spending her free time in the fuzzy set. 
Lauren Rearick, PEOPLE.com, 12 Jan. 2022 Professor Zadeh originally envisioned fuzzy sets as simply a framework for harnessing language. Cade Metz, New York Times, 11 Sep. 2017
Lauren Rearick, PEOPLE.com, 12 Jan. 2022 Professor Zadeh originally envisioned fuzzy sets as simply a framework for harnessing language. Cade Metz, New York Times, 11 Sep. 2017 Word History
First Known Use
1964, in the meaning defined above