Online Etymology Dictionary

cannon: c.1400, "tube for projectiles," from O.Fr. canon (14c.), from It. cannone "large tube," augmentive of L. canna "reed, tube" (see cane). Cannon fodder (1891) translates Ger. kanonenfutter (cf. Shakespeare's food for powder in "I Hen. IV"). Spelling not differentiated from canon till c.1800. Cannon ball is from 1660s.
cannonade: "discharge of artillery," 1650s, from cannon + -ade. As a verb, from 1660s. Cf. Fr. canonnade (16c.), It. cannonata.
mortar (3): "short cannon," 1558, originally mortar-piece, from M.Fr. mortier "short cannon," from O.Fr. "bowl for mixing or pounding" (see mortar (2)). So called for its shape.
gun: mid-14c., gunne "an engine of war that throws rocks, arrows or other missiles," probably a shortening of woman's name Gunilda, found in M.E. gonnilde "cannon" and in an Anglo-L. reference to a specific gun from a 1330 munitions inventory of Windsor Castle ("...una magna balista de cornu quae Domina Gunilda ..."), from O.N. Gunnhildr, woman's name (from gunnr + hildr, both meaning "war, battle"); the identification of women with powerful weapons is common historically (cf. Big Bertha, Brown Bess, etc.); meaning shifted with technology, from cannons to firearms as they developed 15c. Great guns (cannon, etc.) distinguished from small guns (such as muskets) from c.1400. First applied to pistols and revolvers 1744. Meaning "thief, rascal" is from 1858. The verb meaning "to shoot with a gun" is from 1620s; the sense of "to accelerate an engine" is from 1930. Gun-shy is 1884, originally of sporting dogs. Son of a gun is originally nautical. Gun-metal (commonly an alloy of copper and zinc) used attributively of a dull blue-gray color since 1905.
gunner: mid-14c., gonner “one who works a cannon,” agent noun from gun.
germane: mid-14c., "having the same parents," derived from german (1); cf. human/humane, urban/urbane. Main modern sense of "closely connected, relevant" (c.1600) derives from use in "Hamlet" Act V, Scene ii: "The phrase would bee more Germaine to the matter: If we could carry Cannon by our sides," which is a fig. use of the word in the now-obsolete sense of "closely related, akin" (late 15c.) in reference to things, not persons.
trunnion: 1620s, "either of two round projections of a cannon," from Fr. trognon "core of fruit, stump, tree trunk," from M.Fr. troignon (14c.), probably, from L. truncus (see trunk).
Quaker: 1651, said to have been applied to them in 1650 by Justice Bennett at Derby, from George Fox's admonition to his followers to "tremble at the Word of the Lord;" but the word was used earlier of foreign sects given to fits of shaking during religious fervor, and that is likely the source here. Either way, it was never an official name of the Religious Society of Friends. Quaker gun (1809, Amer.Eng.) was a log painted black and propped up to look from a distance like a cannon, so called for the sect's noted pacifism.
flak: 1938, from Ger. Flak, acronym for Fliegerabwehrkanone "airplane defense cannon." Sense of "anti-aircraft fire" is 1940; metaphoric sense of "criticism" is c.1963 in Amer.Eng.
loggerhead: 1580s, "stupid person, blockhead," from dial. logger "heavy block of wood." Later it meant "a thick-headed iron tool" (1680s), a type of cannon shot, a type of turtle (1650s). Loggerheads "fighting, fisticuffs" is from 1670s, but the exact notion is uncertain, perhaps it suggests the heavy tools used as weapons. The phrase at loggerheads "in disagreement" is first recorded 1831.
shrapnel: 1806, from Gen. Henry Shrapnel (1761-1842), who invented a type of exploding, fragmenting shell when he was a lieutenant in the Royal Artillery during the Peninsular War. The invention consisted of a hollow cannon ball, filled with shot, which burst in mid-air; his name for it was spherical case ammunition. Sense of "shell fragments" is first recorded 1940. The surname is attested from 13c., and is believed to be a metathesized form of Charbonnel, a dim. form of O.Fr. charbon "charcoal," in ref. to complexion, hair color, or some other quality.
basilisk: c.1300, from L. basiliscus, from Gk. basiliskos "little king," dim. of basileus "king" (see Basil); said by Pliny to have been so called because of a crest or spot on its head resembling a crown.
The basilisk has since the fourteenth century been confused with the Cockatrice, and the subject is now a complicated one. [T.H.White]
Its breath and glance were said to be fatal. The South American lizard so called (1813) because it, like the mythical beast, has a crest. Also used of a large cannon, throwing shot of 200 lb., in 1549.
ordnance: "cannon, artillery," a clipped form of ordinance (q.v.) which was attested from late 14c. in the sense of "military materials, provisions of war;" a sense now obsolete but which led to those of "engines for discharging missiles" (early 15c.) and "branch of the military concerned with stores and materials" (late 15c.). The shorter word was established in these distinct senses by 17c. Ordnance survey (1833), official survey of Great Britain and Ireland, was undertaken by the government under the direction of the Master-General of the Ordnance (a natural choice, because gunners have to be skilled at surveying ranges and distances).
loose (adj.): c.1300, from O.N. lauss "loose, free, vacant, dissolute," cognate with O.E. leas "devoid of, false, feigned, incorrect," from P.Gmc. *lausaz (cf. Dan. løs "loose, untied," M.Du., Ger. los, Goth. laus), from PIE *lau-/*leu- "to loosen, divide, cut apart" (see lose). The verb is first recorded early 13c., "to set free." Sense of "unchaste, immoral" is recorded from late 15c. Figurative sense of loose cannon was in use by mid-20c.