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ante meridiem

American  
[an-tee muh-rid-ee-uhm, -em] / ˈæn ti məˈrɪd i əm, -ˌɛm /

adverb

  1. before noon.

ante meridiem British  
/ ˈæntɪ məˈrɪdɪəm /

  1. the full form of a.m.

"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

Etymology

Origin of ante meridiem

First recorded in 1555–65

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.