AM means before noon. This is the 12-hour period from midnight to noon. PM means after noon. It covers the 12 hours from noon to midnight. Using numbers from 1 to 12, followed by am or pm, the 12-hour clock system identifies all 24 hours of the day.

The meaning of AM and PM is the simple abbreviation of Latin phrases. In particular, AM stands for ante meridiem, which translates into English as ‘before midday’. Meanwhile, PM is post meridiem and means in English ‘after midday’. These abbreviations are used to identify the time in the 12-hour clock format instead of using 24 hours.

2019年10月3日 · The term we associate with the morning, a.m., is an abbreviation of the Latin phrase ante merīdiem meaning “before midday.” What does p.m. mean? P.m. is an abbreviation of post merīdiem, meaning—you guessed it—“after midday.” These two terms help keep ambiguity at bay in the 12-hour time system. What does m. mean?

The 12-hour clock is a time convention in which the 24 hours of the day are divided into two periods: a.m. (from Latin ante meridiem, translating to "before midday") and p.m. (from Latin post meridiem, translating to "after midday").

Convert 12 hour time format to 24 hour clock time format, how to calculate 12h AM and PM clock time to 24h time including time conversion table.

时间am的全称是 ante meridiem(before noon)， 上午 （0：00-12：00）。 时间pm的全称是post meridiem (=afternoon) ，下午（12：01-24：00)。 时间单位其指时辰，古时一天分12个时辰

大多数数字时钟和大多数来源，将午夜定为12 am，中午定为12 pm。虽然正午的准确时间不属于这两类，但它之后的时间，从12:00:01到12:59:59，显然是正午以后。为了避免混淆，当提到中午或午夜时，我们建议使用12 noon和12 midnight 。

AM、PM 是什麼意思？ 目前世界通用的時間制有十二小時制和二十四小時制，其中十二小時制等於上下午制，也就是西方常用的 AM/PM 制。 以下為 AM 和 PM 的意思和寫法： A.M. = Ante Meridiem（拉丁文，表示中午之前、上午，before midday），可等於 am、a.m.、AM

There are two main ways to show the time: "24 Hour Clock" or "AM/PM": 24 Hour Clock: the time is shown as how many hours and minutes since midnight. AM/PM (or "12 Hour Clock"): the day is split into:

The meaning of AM and PM is ‘Ante Meridiem’ and ‘Post Meridiem’, which means before noon or midday. We associate P.M. with the afternoon and evening. P.M. is an abbreviated term for ‘Post Meridiem,’ which implies afternoon or after midday.