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]
carom (n.)youdaoicibaDictYouDict
1779, earlier carambole (1775), from French carambole "the red ball in billiards," from Spanish carombola "the red ball in billiards," perhaps originally "fruit of the tropical Asian carambola tree," which is round and orange and supposed to resemble a red billiard ball; from Marathi (southern Indian) karambal. Originally a type of stroke involving the red ball:
If the Striker hits the Red and his Adversary's Ball with his own Ball he played with, he wins two Points; which Stroke is called a Carambole, or for Shortness, a Carrom. ["Hoyle's Games Improved," London, 1779]