a page or series of pages showing the days, weeks and months of a particular year, especially one that you hang on a wall 日历；挂历 
a calendar for 2020/a 2020 calendar 2020年的日历
Culture the calendarthe calendarBritain and the US follow the Gregorian calendar, which replaced the Roman Julian calendar in 1752. The year is divided into 12 months, with 30 or 31 days in each month, except February, which has 28 days. An extra day is added to February every fourth year, called a leap year, to keep the calendar in time with the moon. A well-known verse helps people remember how many days there are in each month:“Thirty days hath September,April, June and November.All the rest have thirty-one,Excepting February alone,Which hath twenty-eight days clear,and twenty-nine in each leap year.”The calendar year starts on 1 January, New Year’s Day. The number of each year (2003, 2004, etc.) represents the number of years that have passed since the birth of Jesus Christ. The year 2000 marked the end of the second millennium (= a period of 1 000 years) since Christ was born. The years before Christ are described as BC (= before Christ), for example, 55 BC, or BCE (= before the Common Era). AD (Latin Anno Domini, meaning ‘in the year of the Lord’) or CE (= Common Era) are put before or after the date for the years after Christ's birth, for example, AD 44 or 44 AD, but they are not used with years after about 200 AD. Some cultural and religious groups use different calendars: the year 2000 in the Gregorian calendar began during the year 5760 in the Jewish calendar, 1420 in the Islamic calendar and 1921 in the Hindu calendar.The academic year used by schools and colleges in Britain runs from September to July, with short holidays at Christmas and in the spring and a long summer vacation. In the US the academic year runs from August or September to May or June. Many business companies have a financial year (= a period of accounting) that runs from April to the following March. The tax year in the US is the same as the calendar year but the tax year in Britain begins on 5 April. The reason is that in the Middle Ages the calendar year began on 25 March, not 1 January. When the Gregorian Calendar was introduced, an adjustment was needed and 11 days were removed from September 1752. To avoid being accused of collecting a full year's taxes in a short year, the government made the end of the 1752-3 tax year 4 April.Many festivals are celebrated during the year. Christmas and Easter are the main Christian festivals. Jews remember Passover and Yom Kippur. Ramadan, a month of fasting (= not eating during the day), and Eid ul-Fitr are celebrated by Muslims. Diwali, the Hindu festival of light, takes place in October or November, and the Chinese celebrate their new year in January or February. Special occasions such as Bonfire Night in Britain and Thanksgiving in the US are enjoyed by almost everyone.Oxford Collocations Dictionaryadjective- busy
- full
- sporting
- …
- check
- consult
- in a/the calendar
- on a/the calendar
- mark something on the calendar
- put something on the calendar
- (especially North American English)
a record of what you have to do each day; the book or piece of software in which you record this 日程表；记事本（指纸质本或软件） I think I'm free on that day—let me check my calendar. 我想那天我应该有空，让我查一下记事本。
Oxford Collocations Dictionaryadjective- busy
- full
- sporting
- …
- check
- consult
- in a/the calendar
- on a/the calendar
- mark something on the calendar
- put something on the calendar
- [usually singular]
a list of important events or dates of a particular type during the year （一年之中的）重大事件（或重要日期）一览表 This is one of the biggest weeks in the racing calendar. 这是全年赛马日程表中最重要的几个星期之一。 The group has a busy social calendar. 该小组的社交日程表排得满满的。 a major festival in the church’s calendar 教堂日历上的一个重要节日 These days the tennis calendar has become so crowded. 这些天来，网球日程表变得非常拥挤。
Oxford Collocations Dictionaryadjective- busy
- full
- sporting
- …
- check
- consult
- in a/the calendar
- on a/the calendar
- mark something on the calendar
- put something on the calendar
a system by which time is divided into fixed periods, showing the beginning and end of a year 历法 the Islamic calendar 伊斯兰教历
Word OriginMiddle English: from Old French calendier, from Latin kalendarium ‘account book’, from kalendae,calendae ‘first day of the month’ (when accounts were due and the order of days was proclaimed); related to Latin calare and Greek kalein ‘call, proclaim’.