Example sentences
míng明tiān天jiàn见。
See you tomorrow.
míng明tiān天huì会xià下yǔ雨ma吗？
Will it rain tomorrow?
About this word
明 is "bright" and 天 is "day", and the pair means "tomorrow". You cannot guess the meaning from the two characters alone; the pattern is what teaches it. 明 carries a sense of "next, following", the same one in 明年 (next year) and 明晚 (tomorrow evening), so 明天 is the next day, built on the frame that also produces 昨天 and 今天. The frame is worth having, because 天 is the slot that makes a day word and 明 is the slot that pushes it forward. 明天 also points at the near future generally, as in 明天会更好, "tomorrow will be better".
The story behind the character
明
日 (sun) plus 月 (moon). Sun and moon together, that's bright. Xu Shen wrote 明, 照也. No hidden story. Just the most direct compound there is: sun plus moon equals bright.
天
大 is a person with arms spread. Add one stroke on top and you get 天. The space above a person's head. So it didn't start as "sky," it started as "the top of your head." Only later did it climb up to mean heaven.