PM - Wikipedia
https://en.wikipedia.org/wiki/PM
PM or pm (also written P.M. or p.m.) is an abbreviation for Latin post meridiem, meaning "after noon" in the 12-hour clock. PM or Pm may also refer to: Palm mute, a guitar playing technique. PM (Australian radio program). PM (BBC Radio 4), UK. PM Magazine, an American TV news program (1976-1991).
AM and PM: What Do They Mean?
https://www.timeanddate.com/time/am-and-pm.html
What Do AM and PM Stand For? By Aparna Kher. Some countries, including the US, Canada, and Australia, use the 12-hour clock format including Using numbers from 1 to 12, followed by am or pm, the 12-hour clock system identifies all 24 hours of the day. For example, 5 am is early in the morning...
What do AM and PM mean?
https://24timezones.com/am-pm
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 One of the most common ambiguities of AM and PM was the confusion regarding the start of a day. Namely, it is difficult to determine the starting point...
The Time - Converting AM/PM to 24 Hour Clock
https://www.mathsisfun.com/time.html
AM/PM (or "12 Hour Clock"): the day is split into: the 12 Hours running from Midnight to Noon (the AM hours), and. From 1:00 AM to 12:59 PM, no change.
12 Hour AM/PM to 24 Hour Clock Time Conversion
https://www.timecalculator.net/12-hour-to-24-hour-converter
Time (12h am/pm) : AM PM. Simply enter the 12-hour time value into the box on the left and select between ante meridiem (am) or post meridiem (pm) options.