People are just realizing they've been saying AM and PM without actually knowing what they mean

Some things in life are so routine that we rarely stop to question them. Take AM and PM, for example. Most of us use them daily, but their meanings are often overlooked. A viral post by Kuřo Antoine—who goes by @IAMTOINEJ on X (formerly Twitter)—has left people shocked and amused as they realize what the abbreviations stand for.

In his tweet, he asked, "I might be called stupid after this, but what do 'AM' and 'PM' stand for?" The question quickly sparked debate, with reactions ranging from disbelief to curiosity. Some found it hard to believe anyone would not know the answer, while others admitted they had never given it much thought.

@Tarzan_CFC confessed, "Thank you for sacrificing yourself by asking on our behalf." While @krosstalkopenly observed, "I bet 5,000 people got the answer to that question from this post, when they didn't even have the question in them before this post. That makes it a great post. It made people think and answered the question." @HHHCandle shared, "This reminds me of something that happened in the 6th grade. A teacher in the public school told us that AD, as in 200 AD, meant 'After Death,' as in Christ's death. The right answer is Anno Domini, which is Latin for In the Year of our Lord." @RalonNetaph added, "I have looked this up multiple times before and the knowledge never sticks for this one."

Not everyone was impressed with Antoine's question, though. Some sarcastic responses suggested the question could have been Googled. "Wow, this gives me a great idea! What if there was some way on the internet that you could search for answers without having to ask specific people? I think a site that could do that might do very well," @dbsq_x quipped. @luism8989 said, "It's not stupid to not know, but why don't people just Google things? I'm genuinely curious, haha. Happy 2025." @Rowdy_Ferret chimed in, "Sir, do you not have a phone with Google search installed? You could have saved yourself the embarrassment of not knowing how to search something up."

However, some defended the post, pointing out how easy it is to forget seemingly basic information. "I was told the answer once in school. I forgot the full meaning of it. I only remember that one is before noon and the other is afternoon," @TMTinkerer said. @smileswithchar agreed, "I swiftly came to the comments because I realized I didn't know what they stood for either 32 years on this planet."

So, what do the abbreviations mean? The letters AM and PM originate from Latin, according to Unilad. AM stands for ante meridiem, meaning "before midday," while PM stands for post meridiem, which translates to "after midday." Royal Museums Greenwich explains that neither noon nor midnight fits neatly into the AM or PM category, per the outlet. While noon is the dividing line between morning and afternoon, midnight sits at the transition between two days, making it a unique point in time.

This system divides the day into two 12-hour periods, helping differentiate between morning and afternoon. The origins of AM and PM date back to ancient civilizations, including Egypt and Mesopotamia, per MSN. Early societies used sundials and water clocks to divide the day into segments, with Romans later adopting a 12-hour system that divided daylight and nighttime. The length of these hours varied with the seasons. The terms became standardized with the rise of mechanical clocks in medieval Europe. By the time of the Industrial Revolution, AM and PM had cemented themselves as key elements of modern timekeeping.