What are a.m. and p.m.?

When you get up at 2 a.m. Saturday night (actually Sunday morning) to change your clocks for daylight-saving time, here are some answers to questions you may have pondered.

What are the "a.m." and the "p.m." that follow times?

According to the American Heritage Dictionary of the English Language, Fourth Edition, "a.m." is an adverb and an adjective.

It comes from the Latin term "ante meridiem." "Ante" means "before" and "meridiem" means "noon." When placed after a specific time, such as 2, you know that it’s two o’clock before noon, not after.

The abbreviation "p.m.," also an adverb and adjective, comes from the Latin term "post meridiem," or "after noon."

So, when you’re changing your clocks Sunday at 2 a.m., you’ll know that it’s two o’clock before noon because of our language’s Latin roots.

—Michael Picarella