conkeryoudaoicibaDictYouDict[conker 词源字典]
conker: [19] A conker was originally a ‘snail shell’. Small boys tied them on to pieces of string and played a game involving trying to break their opponent’s shell (another method of playing was simply to press two shells together and see which one broke). The first record of the use of horse chestnuts instead of snail shells is from the 1880s, but in the succeeding century this has established itself as the word’s sole application.

It is not entirely clear where it originally came from. The connection with molluscs has inevitably suggested a derivation from conch (itself ultimately from Greek kónkhē), but early 19th-century spellings of the game as conquering, and of conker as conqueror, point to a simpler explanation, that the stronger snail shell defeated, or ‘conquered’, the weaker.
[conker etymology, conker origin, 英语词源]
conker (n.)youdaoicibaDictYouDict
"snail shell," also "horse chestnut," from children's game of conkers (q.v.).