Entry 1 sense Webster, 1913

Antemeridian

/ănˌ-təm-ĕr-ĭd'-ē-ən/ · An·te·me·rid·i·an · IPA /ˌæntəmɛrˈɪdiːən/

01 a. Being before noon; in or pertaining to the forenoon. (Abbrev. a. m.)