不见得 (bú jiàn dé): not necessarily; not likely

Don't assume that expensive things are necessarily good; cheap ones aren't necessarily bad either.

Although he usually doesn't talk much, that doesn't necessarily mean he doesn't understand social niceties.

This restaurant has high ratings online, but in reality it's not necessarily that good.

Working hard doesn't necessarily mean immediate success, but without hard work, you definitely have no chance.

Everyone thinks he will definitely win, but I don't think so; the outcome of the game is still hard to predict.

Rainy days aren't necessarily cool; sometimes they're even more muggy.