What is the definition of erly?

"Erly" is not a recognized English word. It's likely a misspelling of "early".

If you meant to ask about the definition of early, it means:

* Happening or done before the expected or usual time: *She arrived early for the meeting.*

* Near the beginning of a period of time: *He was one of the early pioneers of the internet.*

Let me know if you had something else in mind!