"weapon with a long shaft and a pointed metal head," 1510s, from French pique "a spear; pikeman," from piquer "to pick, puncture, pierce," from Old French pic "sharp point or spike," a general continental term (Spanish pica, Italian picca, Provençal piqua), perhaps ultimately from a Germanic [Barnhart] or Celtic source (see pike (n.2)). An alternative explanation traces the Old French word (via Vulgar Latin *piccare "to prick, pierce") to Latin picus "woodpecker." No doubt, too, there is influence from pike (n.1), which by 1200 had a sense of "spiked staff."
"Formerly the chief weapon of a large part of the infantry; in the 18th c. superseded by the bayonet" [OED]; hence old expressions such as pass through pikes "come through difficulties, run the gauntlet;" push of pikes "close-quarters combat." German Pike, Dutch piek, Danish pik, etc. are from French pique.
late 12c., "stake or rod of iron used to fasten a door or gate," from Old French barre "beam, bar, gate, barrier" (12c.), from Vulgar Latin *barra "bar, barrier," which some suggest is from Gaulish *barros "the bushy end" [Gamillscheg, etc.], but OED regards this as "discredited" because it "in no way suits the sense."
General sense of "anything which obstructs, hinders, or impedes" is from 1530s. Of soap, by 1833; of candy, by 1906 (the process itself dates to the 1840s), both from resemblance of shape. Meaning "bank of sand across a harbor or river mouth" is from 1580s, probably so called because it was an obstruction to navigation. Bar graph is attested from 1925. Bar code first recorded 1963. Behind bars "in prison" is attested by 1934, American English. Welsh bar "a bar, rail," Irish barra "a bar, spike" are said to be from English; German Barre, Danish barre, Russian barŭ are from Medieval Latin or Romanic.
measure of length, Old English gerd (Mercian), gierd (West Saxon) "rod, staff, stick; measure of length," from West Germanic *gazdijo, from Proto-Germanic *gazdjo "stick, rod" (source also of Old Saxon gerda, Old Frisian ierde, Dutch gard "rod;" Old High German garta, German gerte "switch, twig," Old Norse gaddr "spike, sting, nail"), from PIE root *ghazdh-o- "rod, staff, pole" (source also of Latin hasta "shaft, staff"). The nautical yard-arm retains the original sense of "stick."
Originally in Anglo-Saxon times a land measure of roughly 5 meters (a length later called rod, pole, or perch). Modern measure of "three feet" is attested from late 14c. (earlier rough equivalent was the ell of 45 inches, and the verge). In Middle English and after, the word also was a euphemism for "penis" (as in "Love's Labour's Lost," V.ii.676). Slang meaning "one hundred dollars" first attested 1926, American English. Middle English yerd (Old English gierd) also was "yard-land, yard of land," a varying measure but often about 30 acres or a quarter of a hide.
1921, in U.S. humorist Frederick J. Allen's piece "The Goon and His Style" (Harper's Monthly Magazine, December 1921), which defines it as "a person with a heavy touch," one who lacks "a playful mind;" perhaps a made-up word, or from gony "simpleton" (1580s), which was applied by sailors to the albatross and similar big, clumsy birds. Goons were contrasted with jiggers, and the columns about them had some currency in U.S. newspapers c. 1921-25.
A goon is a person with a heavy touch as distinguished from a jigger, who has a light touch. ... Most Germans are goons; most French jiggers. ["A 'Goon' and His Style," in Lincoln State Journal, Dec. 9, 1921]
The word turns up in various places early 20c.: As a mythical monster in a children's serialized story in the U.S. from 1904, as the name of a professional wrestler in North Carolina in 1935. The goons were characters in the "Thimble Theater" comic strip (starring Popeye) by U.S. cartoonist E.C. Segar (1894-1938); they appeared in Segar's strips from mid-1930s and, though they reportedly gave children nightmares, enjoyed a burst of popularity when they appeared in animated cartoons in 1938.
The most famous was Alice the Goon, slow-witted and muscular (but gentle-natured) character who began as the Sea Hag's assistant. Segar might have got the word directly from sailors' jargon.
Later 20c. senses of the word all probably stem from this: Sense of "hired thug" is first recorded 1938 (in reference to union "beef squads" used to cow strikers in the Pacific Northwest). She also was the inspiration for British comedian Spike Milligan's "The Goon Show." Also used among American and British POWs in World War II in reference to their German guards. What are now "juvenile delinquents" were in the 1940s sometimes called goonlets.