[am] [ME, fr. OE eom; akin to ON em am, L sum, Gk eimi] pres 1st sing of be AM n, often attrib [amplitude modulation] (1940): a broadcasting system using amplitude modulation; also: a radio receiver of such a system
AM
Meaning of AM in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012