Online Etymology Dictionary

Internet (n.): 1984, "the linked computer networks of the U.S. Defense Department," shortened from internetwork, inter-network, which was used from 1972 in reference to (then-hypothetical) networks involving many separate computers. From inter- "between" + network (n.).
ethernet (n.): 1980, from ether + ending as in Internet, etc.
netizen (n.): 1995, from net, short for Internet + citizen.
netiquette (n.): 1993, coined punningly from net, short for Internet + etiquette.
webmaster (n.): 1993, from web in the Internet sense + master (n.).
brb: by 1996, Internet chat acronym for be right back.
btw: Internet abbreviation of by the way, in use by 1989.
website (n.): also web site, 1994, from web in the Internet sense + site.
omg: Internet chat abbreviation of oh my God, by 1994. (Earlier in computerese it meant Object Management Group, 1989, a consortium which helped pave the way for the modern Internet.)
broadband (n.): type of high-speed Internet access widely available from 2006, from broad (adj.) + band (n.1).
surf (v.): "ride the crest of a wave," 1917, from surf (n.). Related: Surfed; surfing. In the Internet sense, first recorded 1993.
click-bait (n.): Internet content meant primarily to lure a viewer to click on it, by 2011, from click (n.) + bait (n.).
MapQuest: Internet mapping service, known by that name from 1996; acquired by AOL in 2000. As a verb, by 1997.
leet (n.2): ASCII alternative alphabet used mostly in Internet chat, by 1997, derived from elite (adj.), and sometimes the word also was used as an adjective in that sense in online gaming.
yahoo (n.): "a brute in human form," 1726, from the race of brutish human creatures in Swift's "Gulliver's Travels." "A made name, prob. meant to suggest disgust" [Century Dictionary]. "Freq. in mod. use, a person lacking cultivation or sensibility, a philistine; a lout; a hooligan" [OED]. The internet search engine so called from 1994.
grok (v.): "to understand empathically," 1961, arbitrary formation by U.S. science fiction writer Robert A. Heinlein (1907-1988) in his book "Stranger in a Strange Land." In popular use 1960s; perhaps obsolete now except in internet technology circles.
viral (adj.): "of the nature of, or caused by, a virus," 1944, see virus + -al (1). Sense of "become suddenly widely popular through Internet sharing" is attested by 1999, originally in reference to marketing and based on the similarity of the effect to the spread of a computer virus. Related: Virally.
ARPANET: acronym from Advanced Research Projects Agency Network, set up in 1969 by a branch of the U.S. Department of Defense in partnership with four universities; acknowledged as "the world's first operational packet switching network" and predecessor of the Internet.
Isidore: masc. proper name, from French, from Latin Isidorus, from Greek Isidoros, literally "gift of Isis," from Isis (see Isis) + doron "gift" (see date (n.1)). St. Isidore, archbishop of Seville (600-636) wrote important historical, etymological, and ecclesiastical works and in 2001 was named patron saint of computers, computer users, and the Internet. Related: Isidorian.
domain (n.): early 15c., in Scottish, from Middle French domaine "domain, estate," from Old French demaine "lord's estate," from Latin dominium "property, dominion," from dominus "lord, master, owner," from domus "house" (see domestic). Form influenced in Old French by Medieval Latin domanium "domain, estate." Internet domain name attested by 1985.
fisk (v.): 2002, an Internet argument tactic involving a reprinting of a text, interlarded with rebuttals and refutations. Named for English journalist Robert Fisk (b.1946), Middle East correspondent for the "Independent," whose writing often criticizes America and Israel and is somewhat noted for looseness with details. Critics responded in this style. Related: Fisked; fisking.
web (n.): Old English webb "woven fabric, woven work, tapestry," from Proto-Germanic *wabjam "fabric, web" (source also of Old Saxon webbi, Old Norse vefr, Dutch webbe, Old High German weppi, German gewebe "web"), from PIE *webh- "to weave" (see weave (v.)).

Meaning "spider's web" is first recorded early 13c. Applied to the membranes between the toes of ducks and other aquatic birds from 1570s. Internet sense is from 1992, shortened from World Wide Web (1990). Web browser, web page both also attested 1990.
spam (n.): proprietary name registered by Geo. A. Hormel & Co. in U.S., 1937; probably a conflation of spiced ham. Soon extended to other kinds of canned meat.

In the sense of "Internet junk mail" it was coined by Usenet users after March 31, 1993, when Usenet administrator Richard Depew inadvertently posted the same message 200 times to a discussion group. The term had been used in online text games, and ultimately it is from a 1970 sketch on the British TV show "Monty Python's Flying Circus" wherein a reading of a restaurant's menu devolves into endless repetitions of "spam."
bot (n.): in Internet sense, c. 2000, short for robot. Its modern use has curious affinities with earlier uses, such as "parasitical worm or maggot" (1520s), of unknown origin; and Australian-New Zealand slang "worthless, troublesome person" (World War I-era). The method of minting new slang by clipping the heads off words does not seem to be old or widespread in English. Examples (za from pizza, zels from pretzels, rents from parents) are American English student or teen slang and seem to date back no further than late 1960s.
fascism (n.): 1922, originally used in English in 1920 in its Italian form fascismo (see fascist). Applied to similar groups in Germany from 1923; applied to everyone since the Internet.
A form of political behavior marked by obsessive preoccupation with community decline, humiliation or victimhood and by compensatory cults of unity, energy and purity, in which a mass-based party of committed nationalist militants, working in uneasy but effective collaboration with traditional elites, abandons democratic liberties and pursues with redemptive violence and without ethical or legal restraints goals of internal cleansing and external expansion. [Robert O. Paxton, "The Anatomy of Fascism," 2004]
cyber: as an element in word formation, ultimately from cybernetics (q.v.). It enjoyed explosive use with the rise of the Internet early 1990s. One researcher (Nagel) counted 104 words formed from it by 1994. Cyberpunk (by 1986) and cyberspace were among the earliest.
Cyber is such a perfect prefix. Because nobody has any idea what it means, it can be grafted onto any old word to make it seem new, cool -- and therefore strange, spooky. ["New York" magazine, Dec. 23, 1996]
As a stand-alone, it is attested by 1998 as short for cybersex (which is attested by 1995).
mail-order (adj.): 1875, from mail (n.1) + order. Before television and the Internet, the bane of retailers and shop-owners.
The origin, foundation and principle of mail order trading is universally recognized as wrong. It was conceived in iniquity and brought forth in despair as the world's greatest destructive medium. Mail Order Trading was born in the brain of knaves and thieves who fired their building for insurance profits, then sold the salvaged and damaged stock to the unsuspecting sons of man in distant territory. [Thomas J. Sullivan, "Merchants and Manufacturers on Trial," Chicago, 1914]
coulrophobia (n.): "morbid fear of clowns," by 2001 (said in Web sites to date from 1990s or even 1980s), a popular term, not from psychology, possibly facetious, though the phenomenon is real enough; said to be built from Greek kolon "limb," with some supposed sense of "stilt-walker," hence "clown" + -phobia.

Ancient Greek words for "clown" were sklêro-paiktês, from paizein "to play (like a child);" or deikeliktas; other classical words used for theatrical clowns were related to "rustic," "peasant" (compare Latin fossor "clown," literally "laborer, digger," related to fossil).

The whole creation looks suspiciously like the sort of thing idle pseudo-intellectuals invent on the Internet and which every smarty-pants takes up thereafter; perhaps it is a mangling of Modern Greek klooun "clown," which is the English word borrowed into Greek.
golf (n.): mid-15c., Scottish gouf, usually taken as an alteration of Middle Dutch colf, colve "stick, club, bat," from Proto-Germanic *kulth- (source also of Old Norse kolfr "clapper of a bell," German Kolben "mace, club, butt-end of a gun"). The game is from 14c., the word is first mentioned (along with fut-bol) in a 1457 Scottish statute on forbidden games (a later ordinance decrees, "That in na place of the realme thair be vsit fut-ballis, golf, or vther sic unprofitabill sportis" [Acts James IV, 1491, c.53]). Despite what you read on the Internet, "golf" is not an acronym (this story seems to date back no earlier than 1997). Golf ball attested from 1540s; the motorized golf-cart from 1951. Golf widow is from 1890.
Oh! who a golfer's bride would be,
Fast mated with a laddie
Who every day goes out to tee
And with him takes the caddie.

["The Golf Widow's Lament," in "Golf," Oct. 31, 1890]
fuck (v.): "to have sexual intercourse with" (transitive), until recently a difficult word to trace in usage, in part because it was omitted as taboo by the editors of the original OED when the "F" entries were compiled (1893-97). Johnson also had excluded the word, and fuck wasn't in a single English language dictionary from 1795 to 1965. "The Penguin Dictionary" broke the taboo in the latter year. Houghton Mifflin followed, in 1969, with "The American Heritage Dictionary," but it also published a "Clean Green" edition without the word, to assure itself access to the public high school market.

Written form attested at least from early 16c.; OED 2nd edition cites 1503, in the form fukkit, and the earliest attested appearance of current spelling is 1535 ("Bischops ... may fuck thair fill and be vnmaryit" [Sir David Lyndesay, "Ane Satyre of the Thrie Estaits"]). Presumably it is a more ancient word, but one not written in the kind of texts that have survived from Old English and Middle English [September 2015: the verb appears to have been found recently in an English court manuscript from 1310]. Buck cites proper name John le Fucker from 1278, but that surname could have other explanations. The word apparently is hinted at in a scurrilous 15c. poem, titled "Flen flyys," written in bastard Latin and Middle English. The relevant line reads:
Non sunt in celi
quia fuccant uuiuys of heli
"They [the monks] are not in heaven because they fuck the wives of [the town of] Ely." Fuccant is pseudo-Latin, and in the original it is written in cipher. The earliest examples of the word otherwise are from Scottish, which suggests a Scandinavian origin, perhaps from a word akin to Norwegian dialectal fukka "copulate," or Swedish dialectal focka "copulate, strike, push," and fock "penis." Another theory traces the Modern English verb to Middle English fyke, fike "move restlessly, fidget" (see fike) which also meant "dally, flirt," and probably is from a general North Sea Germanic word (compare Middle Dutch fokken, German ficken "fuck," earlier "make quick movements to and fro, flick," still earlier "itch, scratch;" the vulgar sense attested from 16c.). This would parallel in sense the vulgar Middle English term for "have sexual intercourse," swive, from Old English swifan "to move lightly over, sweep" (see swivel). But OED remarks that these "cannot be shown to be related" to the English word. Liberman has this to say:
Germanic words of similar form (f + vowel + consonant) and meaning 'copulate' are numerous. One of them is G. ficken. They often have additional senses, especially 'cheat,' but their basic meaning is 'move back and forth.' ... Most probably, fuck is a borrowing from Low German and has no cognates outside Germanic.
Chronology and phonology rule out Shipley's attempt to derive it from Middle English firk "to press hard, beat." The unkillable urban legend that this word is an acronym of some sort (a fiction traceable on the Internet to 1995 but probably predating that), and the "pluck yew" fable, are results of ingenious trifling (also see here). The Old English verb for "have sexual intercourse with" was hæman, from ham "dwelling, home," with a sense of "take home, co-habit." French foutre and Italian fottere seem to resemble the English word but are unrelated, descending rather from Latin futuere, which perhaps is from PIE root *bhau(t)- "knock, strike off," extended via a figurative use "from the sexual application of violent action" [Shipley; compare the sexual slang use of bang, etc.].

Fuck was outlawed in print in England (by the Obscene Publications Act, 1857) and the U.S. (by the Comstock Act, 1873). The word continued in common speech, however. During World War I: "It became so common that an effective way for the soldier to express this emotion was to omit this word. Thus if a sergeant said, 'Get your ----ing rifles!' it was understood as a matter of routine. But if he said 'Get your rifles!' there was an immediate implication of urgency and danger." [John Brophy, "Songs and Slang of the British Soldier: 1914-1918," pub. 1930]. The legal barriers against use in print broke down in mid-20c. with the "Ulysses" decision (U.S., 1933) and "Lady Chatterley's Lover" (U.S., 1959; U.K., 1960). The major breakthrough in publication was James Jones' "From Here to Eternity" (1950), with 50 fucks (down from 258 in the original manuscript).

The abbreviation F (or eff) probably began as euphemistic, but by 1943 it was regarded as a cuss word in its own right. In 1948, the publishers of "The Naked and the Dead" persuaded Norman Mailer to use the euphemism fug. When Mailer later was introduced to Dorothy Parker, she greeted him with, "So you're the man who can't spell 'fuck' " [The quip sometimes is attributed to Tallulah Bankhead]. Hemingway used muck in "For Whom the Bell Tolls" (1940). Related: Fucked; fucking. Fuck-all "nothing" first recorded 1960. Verbal phrase fuck up "to ruin, spoil, destroy" is attested from c. 1916. A widespread group of Slavic words (such as Polish pierdolić) can mean both "fornicate" and "make a mistake." Fuck off attested from 1929; as a command to depart, by 1944. Egyptian legal agreements from the 23rd Dynasty (749-21 B.C.E.) frequently include the phrase, "If you do not obey this decree, may a donkey copulate with you!" [Reinhold Aman, "Maledicta," Summer 1977].