An adjective describing ANYTHING. This can only be used when said described object has a characteristic similar to two Chuck Norris round-house kicks colliding with three FALCON PAWNCH!es. Very few things achieve this.
That man with a chain-gun riding a cyborgraptor with a chain-saw arm is EPICLOLZ!
When some resigns or retires from a job, they are on "eternity leave". This can also refer to someone who has passed away, especially someone who worked somewhere for a long time, retired/resigned, then passed away later.
Oh I'm sorry, you didn't know that Kelly is on eternity leave? She resigned and moved to Hawaii!
With regrets I would like to inform you that my boss is officially on eternity leave. I will never see or hear them again. Ever.