1765, "authenticated official report concerning some event, issued for the information of the public," from French bulletin (16c.), modeled on Italian bulletino, diminutive of bulletta "document, voting slip," itself a diminutive of Latin bulla "round object" (see bull (n.2)) with equivalent of Old French -elet (see -let). For use of balls in voting, see ballot (n.).
The word was used earlier in English in the Italian form (mid-17c.). It was popularized by the use of bulletin in the Napoleonic Wars as the name for dispatches sent from the front and meant for the home public (which led to the proverbial expression as false as a bulletin). The broadcast news sense of "any brief, notice or public announcement of news" is from 1925. Bulletin board "public board on which news and notices are posted" is from 1831; computer sense is from 1979.
early 14c., "to train or instruct in some specific subject," from Old French informer, enformer "instruct, teach" (13c.) and directly from Latin informare "to shape, give form to, delineate," figuratively "train, instruct, educate," from in- "into" (from PIE root *en "in") + formare "to form, shape," from forma "form" (see form (n.)). In early use also enform until c. 1600. Sense of "report facts or news, communicate information to" first recorded late 14c. Related: Informed; informing.
"announcement of an event," c. 1200, from late Old English tidung "event, occurrence, piece of news," verbal noun from Old English tidan "to happen," or in part from Old Norse tiðendi (plural) "events, news," from tiðr (adj.) "occurring," both from Proto-Germanic tīdōjanan, from PIE *di-ti- "division, division of time," suffixed form of root *da- "to divide." Similar formation in Norwegian tidende "tidings, news," Dutch tijding, German Zeitung "newspaper."
1560s, "sudden burst of flame or light," from flash (v.); originally of lightning. Figuratively (of wit, laughter, anger, etc.) from c. 1600. Meaning "period occupied by a flash, very short time" is from 1620s. Sense of "superficial brilliancy" is from 1670s. Meaning "first news report" is from 1857. The comic book character dates to 1940. Meaning "photographic lamp" is from 1913. Flash cube (remember those?) is from 1965.
Flash in the pan (1704 literal, 1705 figurative) is from old-style firearms, where the powder might ignite in the pan but fail to spark the main charge; hence figurative sense "brilliant outburst followed by failure."