cannonyoudaoicibaDictYouDict[cannon 词源字典]
cannon: English has two different words cannon, neither of which can for certain be connected with canon. The earlier, ‘large gun’ [16], comes via French canon from Italian cannone ‘large tube’, which was a derivative of canna ‘tube, pipe’, from Latin canna (source of English cane). Cannon as in ‘cannon off something’ [19] is originally a billiards term, and was an alteration (by association with cannon the gun) of an earlier carom (the form still used in American English).

This came from Spanish carombola, a kind of fruit fancifully held to resemble a billiard ball, whose ultimate source was probably an unrecorded *karambal in the Marathi language of south central India.
=> cane; carom[cannon etymology, cannon origin, 英语词源]
cannon (n.)youdaoicibaDictYouDict
c. 1400, "tube for projectiles," from Anglo-French canon, Old French canon (14c.), from Italian cannone "large tube, barrel," augmentative of Latin canna "reed, tube" (see cane (n.)). Meaning "large ordnance piece," the main modern sense, is from 1520s. Spelling not differentiated from canon till c. 1800. Cannon fodder (1891) translates German kanonenfutter (compare Shakespeare's food for powder in "I Hen. IV").