I cannot imagine all of the things I never would have learned of it were not for my Great Inquisitor - Zak. I have studied the whats and hows of countless subjects from exactly how tornadoes form to crossbred canines to the history of graphite, just so I can answer his endless questions.
Today was no exception. During his math work, he looks up and asks, "what does a.m. and p.m. stand for?"
"Ummm...I don't know. I'll have to look it up."
"Whatever it is, I'm sure it's Latin," I mumble as google.
And of course, I learned a few other interesting facts along the way. Here's the highlights, in case your kids ever ask.
The 12-hour clock is a time convention in which the 24 hours of the day are divided into two periods:a.m. (from the Latin ante meridiem, meaning "before midday") and p.m. (post meridiem, "after midday").
The Romans also used a 12-hour clock: daylight was divided into 12 equal hours (of, thus, varying length throughout the year) and the night was divided into four watches. The Romans numbered the morning hours originally in reverse. For example, "3 a.m." or "3 hours ante meridiem" meant "three hours before noon", compared to the modern usage of "three hours into the first 12-hour period of the day".
The 12-hour clock in speech often uses phrases such as in the morning, in the afternoon, in the evening, and at night. Outside of English-speaking countries, the terms a.m. and p.m. are seldom used and often unknown.
So then, now we know. Pleasant p.m. everyone!