What is the abbreviation for Enums?

Answer 1

Enum is the abbreviated form of Enumeration or enumerate. This means to begin to number or list.

Answer 2

Maybe "enumeration type"?

https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html
https://docs.oracle.com/javase/8/docs/api/java/lang/Enum.html
https://en.m.wikipedia.org/wiki/Enumerated_type#Java