a.m.

morning, time before noon; hours between midnight and noon; nickname for a morning newspaper (distributed very late at night)

The 12-hour clock is a timekeeping convention in which the 24 hours of the day are divided into two periods called ante meridiem (a.m., from Latin, meaning "before mid day", or "before the middle of the day") and post meridiem (p.m., "after mid day" or "after the middle of the day"). Each period consists of 12 hours numbered 12 (acting as zero), 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11. Twelve o'clock is either noon or midnight.
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AM or Am may refer to:Artium Magister, alternative abbreviation for a Master's degree in ArtsAmericium, a chemical element with symbol AmArthur-Merlin protocol, an interactive proof system in computational complexity theoryAutomated Mathematician, an artificial intelligence programAttometre (am), a unit of length (equal to 10–18 m)Order of Australia member (postnominal)Accelerated Math in the US or Accelerated Maths in the UK
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Adverb
1. before noon; "let's meet at 11 A.M."
(synonym) ante meridiem
(classification) Latin

Adjective
1. before noon
(synonym) ante meridiem
(similar) antemeridian

AM, amplitude modulation; broadcasting through variations in the width of the radio wave (Electricity)

on the Main

A.M., morning, time before noon; hours between midnight and noon; nickname for a morning newspaper (distributed very late at night)