Looking up...
我们聊了半天天气。
We talked about the weather for half a day.
Half a day; a long time (informal)
他半天才回复我的消息。
He took half a day to reply to my message.
Often used to express that something took a long time or was delayed.
While it literally means 'half a day,' it's often used to emphasize that something took a long time.
Combination of 半 (half) and 天 (day).
Can be used literally to mean half a day or figuratively to mean a long time.