白【bái】

白 before a verb says the action happened but got nothing for it. It's spoken and usually comes with 了, since the waste is already done.

Before something not yet done, it says there's no point doing it.

白白 is the same, with more regret in it.

没白

没白 + verb says the effort paid off.

For free

With 吃, 拿 and 用, 白 can also mean "without paying". Context decides; 白吃 is usually "eat for free".

Where it goes

白 is an adverb, so it sits before the verb, not after it as "wasted" would in English.

• × 我跑白了 → 我白跑了