This is the 5948th most frequent Chinese word.
天內
"天內" means "within the day."
The term '天內' is used in the context of specifying a timeframe within which an action needs to be completed, emphasizing the duration restricted within specified days.
我需要在三天以内完成这个工作。
I need to finish this work within three days.
Here, '天內' again denotes a period within which something—a completion of the event—is going to happen.
活动将在两天内结束，请抓紧时间参加。
The event will conclude within two days, please make sure to participate in time.
The usage of '天內' specifies an estimated maximum duration (five days) for the completion of the delivery process.