Abbreviation of 月曜日 (げつようび). Used in schedules, calendars, and casual speech.
See also: 月曜日
会議は月曜の午前中です。
The meeting is on Monday morning.
月曜から金曜まで働いています。
I work from Monday to Friday.
This restaurant is closed on Mondays.
I have an exam on Monday.
The trains are crowded on Monday mornings.