1767, "dispersed upon the ground by hand," in reference to seed, from broad (adj.) + past participle of cast (v.). The figurative sense of "widely spread" is recorded by 1785. As an adverb from 1832. The modern media use began with radio (1922, adjective and noun). As a verb, recorded from 1813 in an agricultural sense, 1829 in a figurative sense, 1921 in reference to radio.
"one who broadcasts," in any sense, 1922, agent noun from broadcast.
1937, from television + broadcast (n.). The verb is recorded from 1940.
"episodic series of spoken-word digital audio files that can be downloaded to a personal device and listened to at leisure," 2004, noun and verb, from pod-, from iPod, brand of portable media player, + second element abstracted from broadcast. Related: Podcasting.
1922, verbal noun from broadcast (v.).
Broadcasting, as distinct from wireless communication, may be said to have come into being about 1920. It may be defined as the systematic diffusion, by radio telephony, of music, lectures, drama, humour, news and information bulletins, speeches and ceremonies, pictures and other matter susceptible of appreciation by a scattered audience, individually or in groups, with appropriate receiving apparatus. [Encyclopedia Britannica, 1929]