Hi, your question is a little confusing. AM and PM are the abbreviations. They mean morning and afternoon/evening and come from the Latin 'ante meridiem' (before midday) and 'post meridiem' (after midday).

Everyone gave great answers, especially Dan, by the way. Anyway, aren't Americans (from the USA I mean) the only people on the face of the earth dumb enough to still use this anachronistic AM/PM garbage? What's wrong with the 24-hour clock? Oops, too complicated for Americans to figure out! It's as stupid as using feet and inches, and fractions of inches, and Fahrenheit for temperature. Old habits die hard I suppose, ESPECIALLY here in the retarded USA. Tell a German the weather is a beautiful 72 degrees and he'll think you've lost your mind. Or that you are 6 feet tall and he won't have a clue what you are talking about.(Well, I'm sure most know the US way of thinking, but it doesn't make any sense to them).

Not all native English speakers know this, but they are abbreviations for "antemeridian" and "postmeridian." "Meridian" can mean "noon," "ante-" means "before," and "post-" means "after." "Antemeridian" and "postmeridian" are rare, obscure English words that meaning "morning" and "afternoon." We use the abbreviations for these words, but we almost never use the words themselves! Added after reading Elaine's response--I don't mean to contradict her and I do not know whether AM is an abbreviation for the English word "antemeridian" or the Latin term "ante meridiem." Perhaps it is actually an abbreviation used by classical Romans themselves?