noun, adverb
Used as both a noun and an adverbial time expression. It is neutral and common, but can sound a little more written or formal than ゆうべ in casual conversation.
昨晩はよく眠れました。
I slept well last night.
昨晩、東京で地震がありました。
There was an earthquake in Tokyo last night.
昨晩の雨で道がぬれています。
The road is wet from last night's rain.