1. before noon.
  2. the period from midnight to noon, especially the period of daylight prior to noon: Shall we meet Saturday a.m.?
  3. a morning newspaper, sometimes issued shortly before midnight.
Compare p.m.

Origin of a.m.

From the Latin word ante merīdiem

Usage note

The abbreviation a.m. for Latin ante meridiem, meaning “before noon,” refers to the period from midnight until noon. One minute before noon is 11:59 a.m. One minute after noon is 12:01 p.m. Many people distinguish between noon and midnight by saying 12 noon and 12 midnight. Expressions combining a.m. with morning ( 6 a.m. in the morning ) and p.m. with afternoon, evening, or night ( 9 p.m. at night ) are redundant and occur most often in casual speech and writing. Both a.m. and p.m. sometimes appear in capital letters, especially in printed matter.


  1. a.m.
  2. Master of Arts.

Origin of A.M.

From the Latin word Artium Magister

A and M

or A&M

  1. Agricultural and Mechanical (college): Texas A and M.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for a.m.


A.M., am or AM

abbreviation for (indicating the time period from midnight to midday)
  1. ante meridiemCompare p.m.

Word Origin for a.m.

Latin: before noon
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for a.m.

in hours, 1762, abbreviation of Latin ante meridiem "before noon."

also AM, type of radio wave broadcast; see amplitude.

Online Etymology Dictionary, © 2010 Douglas Harper