1795, in specific sense of "government intimidation during the Reign of Terror in France" (March 1793-July 1794), from French terrorisme, noted in English by 1795 as a coinage of the Revolution, from Latin terror "great fear, dread, alarm, panic; object of fear, cause of alarm; terrible news," from PIE root *tres- "to tremble" (see terrible).
If the basis of a popular government in peacetime is virtue, its basis in a time of revolution is virtue and terror — virtue, without which terror would be barbaric; and terror, without which virtue would be impotent. [Robespierre, speech in French National Convention, 1794]
General sense of "systematic use of terror as a policy" is first recorded in English 1798 (in reference to the Irish Rebellion of that year). At one time, a word for a certain kind of mass-destruction terrorism was dynamitism (1883); and during World War I frightfulness (translating German Schrecklichkeit) was used in Britain for "deliberate policy of terrorizing enemy non-combatants."
in the modern sense, 1944, especially in reference to Jewish tactics against the British in Palestine — earlier it was used of extremist revolutionaries in Russia who attempted to demoralize the government by terror (1866); and Jacobins during the French Revolution (1795) — from French terroriste; see terror + -ist (also see terrorism).
The term now usually refers to a member of a clandestine or expatriate organization aiming to coerce an established government by acts of violence against it or its subjects. [OED]
The tendency of one party's terrorist to be another's guerrilla or freedom fighter was noted in reference to the British action in Cyprus (1956) and the war in Rhodesia (1973). The word terrorist has been applied, at least retroactively, to the Maquis resistance in occupied France in World War II (as in in the "Spectator," Oct. 20, 1979).
[circular band] Old English hring "circlet of metal, especially one of a precious metal for wearing on the finger ornamentally, also a part of a mail coat; anything circular," from Proto-Germanic *hringaz "something curved, circle" (source also of Old Norse hringr, Old Frisian hring, Danish, Swedish, Dutch ring, Old High German hring, German Ring), from nasalized form of PIE root *sker- (2) "to turn, bend."
Other Old English senses were "circular group of persons" (birds, actually), also "horizon." In Old and Middle English also "a bracelet, armlet." As a token of marriage, betrothal, chastity, etc., by c. 1200. The sense of "a number of things arranged in a circle" is by 1580s.
The meaning "place for prize fight and wrestling bouts" (early 14c.) is from the space in a circle of bystanders in the midst of which such contests once were held, "... a circle formed for boxers, wrestlers, and cudgel players, by a man styled Vinegar; who, with his hat before his eyes, goes round the circle, striking at random with his whip to prevent the populace from crowding in" [Grose, 1785]. Hence the ring "boxing" (by 1770). The meaning "combination of persons interested in attaining some object" is from 1829, originally commercial or political, latter in reference to espionage or terrorism. Of the annual growth bands in trees, from 1670s.
Fairy ring is from 1620s. Ring finger, "third finger of the left hand" (in anatomy, of either hand) is Old English hringfingr, a compound also attested in other Germanic languages; it is also called ring-man (15c.). To run rings round (someone) "be superior to" is from 1891.
The nursery rhyme ring a ring a rosie is attested in an American form (with a different ending) from c. 1790. "The belief that the rhyme originated with the Great Plague is now almost universal, but has no evidence to support it and is almost certainly nonsense" ["Oxford Dictionary of English Folklore"]. This proposal of connection dates only to the late 1960s.