ちゅうじゅん中旬chuujun
1.

The period in a month that spans from the 11th to the 20th, marking the middle portion of the month.

2.

The segment of time within a month characterized by the middle ten days, specifically from the 11th to the 20th.

3.

A distinct time frame in a month that denotes the days between the 11th and 20th, representing the transition between the early and late parts of the month.

Example:

予定日は1月の中旬頃です。

げつちゅうじゅん月中旬getsuchuujun
1.

The period that occurs approximately halfway through a month, typically characterized by the days around the 15th.

2.

The timeframe during the month when the attention often shifts from the beginning's activities to the concluding events, marking a transitional phase.