What Latin root word means the opposite of brev?

The Latin root word meaning the opposite of "brev" (meaning "short") is long.

Here's why:

* brev is the root of words like "brief," "brevity," and "abbreviate."

* long is the root of words like "long," "length," and "elongate."

Therefore, "long" is the opposite of "brev" in terms of length or duration.