A phenomenon is anything observed happening, especially something remarkable. A natural phenomenon, a social phenomenon, a phenomenon of our time.
In science it is neutral and means an observable event, and in ordinary use it means something extraordinary — the drift is towards the second. The plural is phenomena, and using phenomena as a singular is a common error. Note that the Greek means a thing appearing.
1nounphenomenonAnything observed happening, especially something remarkable.
“The northern lights are a natural phenomenon seen in the far north.”
phenomenon is an observed event.
Greek phainomenon means a thing appearing, from phainein, to show. Fantasy and diaphanous come from the same showing.
Latin
phaenomenon
English, today
phenomenon
Built from
From Latin phaenomenon. From Latin phaenomenon (“appearance”), from Ancient Greek φαινόμενον (“thing appearing to view”), neuter present middle participle of φαίνω (“I show”).
Etymology from Wiktionary, CC BY-SA