calendar

a system of timekeeping that defines the beginning and length and divisions of the year

a list or register of events (appointments or social events or court cases etc)

a tabular array of the days (usually for one year)

An orderly arrangement of the division of time, adapted to the purposes of civil life, as years, months, weeks, and days; also, a register of the year with its divisions; an almanac.

enter into a calendar

To enter or write in a calendar; to register.