as i sit here, i realize i dont know what they mean. im sure its simple as Pre Midnight and After midnight, but im not too sure and dont feel like googling it. thanks amigos! (amigas)
12-hour clock - Wikipedia, the free encyclopedia -AM 12-hour clock - Wikipedia, the free encyclopedia -PM Good question.
Ante meridian and post meridian -- literally before and after the midpoint of the day. And I didn't even go to Wikipedia. :P
“AM” stands for the Latin phrase Ante Meridiem —which means “before noon”—and “PM” stands for Post Meridiem : “after noon.” Edit: Sorry, I see that Steve already gave the correct answer.