月底 (yuè dǐ) means “end of the month”

More examples

请在月底之前把表格填好。qǐng zài yuè dǐ zhī qián bǎ biǎo gé tián hǎo

Please fill out the form before the end of the month.

The point where a month runs out, covering its last few days and its final date.

月末yuè mò: The date or period that marks the end of a month.

指一个月的最后几天或最后一天。zhǐ yí gè yuè de zuì hòu jǐ tiān huò zuì hòu yì tiān

The compound 月底 (yuèdǐ, "end of the month") joins 月 (yuè, "month") and 底 (dǐ, "bottom"), extending the meaning of bottom to the end of a period.

For deadlines, specify whether something happens before or after the month ends, since the term alone does not identify a precise date.