1791, "state or condition of being public or open to the observation and inquiry of a community," from French publicité (1690s), from Medieval Latin publicitatem (nominative publicitas), from Latin publicus (see public (adj.)). Sense of "a making (something) known, an exposure to the public" is from 1826, shading by c. 1900 into "advertising, the business of promotion." Publicity stunt is recorded by 1908.

"a promotional advertisement," 1958 (in Billboard magazine headlines), shortening of promotion in the sense "advertising, publicity."

1972 (in reference to a letter of 1969 by Solzhenitsyn), from Russian glasnost "openness to public scrutiny," literally "publicity, fact of being public," ultimately from Old Church Slavonic glasu "voice," from PIE *gal-so-, from root *gal- "to call, shout." First used in a socio-political sense by Lenin; popularized in English after Mikhail Gorbachev used it prominently in a speech of March 11, 1985, accepting the post of general secretary of the CPSU.

The Soviets, it seems, have rediscovered the value of Lenin's dictum that "glasnost," the Russian word for openness or publicity, is a desirable form of conduct. [New York Times news service article, March 1981]

c. 1400, promocioun, "advancement in rank, honor, or position," from Old French promocion "election, promotion" (14c., Modern French promotion) and directly from Latin promotionem (nominative promotio) "advancement, a moving forward," noun of action from past-participle stem of promovere "move forward, advance" (see promote).

From early 15c. as "advancement of a cause; assistance, help, support, encouragement." The meaning "advertising, publicity" first recorded 1925.

"publicity or press agent," 1945, also by that year as a verb, said to have been coined at show biz magazine Variety (but the first attested use is not in Variety) and supposedly from name of Gene Flack, a movie agent, but influenced by flak. There was a Gene Flack who was an advertising executive in the U.S. during the 1940s, but he seems to have sold principally biscuits, not movies.

by 1953, name for human anti-coagulant use of the rat poison warfarin sodium, abstracted from the chemical name, 3-(α-acetonylbenzyl)-4-hydroxycoumarin; earlier known as Dicoumarol, it attained publicity when it was used in 1955 to treat U.S. President Dwight Eisenhower after a heart attack. Coumarin as the name of an aromatic crystalline substance is by 1830 in English, from French coumarine, from coumarou, the native name in Guyana of the tonka or tonquin bean, one source of the substance.