名詞 a.m.:

1. a radioactive transuranic metallic element; discovered by bombarding uranium with helium atoms
   同義詞：americium, Am, atomic number 95
2. a master's degree in arts and sciences
   同義詞：Master of Arts, MA, Artium Magister, AM
3. modulation of the amplitude of the (radio) carrier wave
   同義詞：amplitude modulation, AM

形容詞 a.m.:

1. before noon
   同義詞：ante meridiem

副詞 a.m.:

1. before noon
   同義詞：ante meridiem