What does the name Eylin mean?

There's no widely accepted, established meaning for the name "Eylin". It's likely a variant spelling of a more common name, possibly:

* Eileen: Of Irish origin, meaning "bright light" or "torch".

* Aileen: A variation of Eileen, also meaning "bright light".

* Eilin: A Scandinavian name with the meaning "light" or "shining".

Without more context, it's impossible to be certain of the intended meaning of "Eylin".