Learner's definition of PHENOMENON
1 pluralphenomena/-ənə//fɪˈnɑːmənə/ : something (such as an interesting fact or event) that can be observed and studied and that typically is unusual or difficult to understand or explain fully 2
pluralphenomenons : someone or something that is very impressive or popular especially because of an unusual ability or quality
the greatest literary phenomenon of the decade
He's a football/baseball phenomenon.
The movie eventually became a cultural phenomenon.