a.m

(noun) a radioactive transuranic metallic element; discovered by bombarding uranium with helium atoms. Synonyms: americium, Am, atomic number 95.

(noun) a master's degree in arts and sciences. Synonyms: Master of Arts, MA, Artium Magister, AM.

(noun) modulation of the amplitude of the (radio) carrier wave. Synonyms: amplitude modulation, AM.