Which word comes from the Latin root meaning book

liber

Explanation:

In the Latin-based languages, the word for “book” is inherited from the Latin word liber, which originally meant “tree bark”, but eventually came to mean “book”. The Latin word liber is essentially identical to another Latin word — līber — which means “free”, but apparently this similarity is a coincidence.

2018 means 2018 ce or common era

there have been other eras too including bce, which included way more years.