collaryoudaoicibaDictYouDict[collar 词源字典]
collar: [13] Etymologically, a collar is simply something worn round one’s ‘neck’. The word comes via Anglo-Norman coler from Latin collāre, which meant ‘necklace’ as well as ‘part of a garment that encircles the neck’ (both senses have come through into English, although the latter has predominated). Collāre was a derivative of collum ‘neck’, which came from an earlier base *kols- that also produced German and Swedish hals ‘neck’.

It has been speculated that it goes back ultimately to Indo-European *qwelo- ‘go round’, the root from which we get English wheel – the underlying notion being that the neck is that on which the head turns.
=> décolleté, hauberk, wheel[collar etymology, collar origin, 英语词源]
collar (n.)youdaoicibaDictYouDict
c. 1300, "neck armor, gorget," from Old French coler "neck, collar" (12c., Modern French collier), from Latin collare "necklace, band or chain for the neck," from collum "the neck," from PIE *kwol-o- "neck" (cognates: Old Norse and Middle Dutch hals "neck"), literally "that on which the head turns," from root *kwel- (1) "move round, turn about" (see cycle (n.)). Late 14c. as "border at the neck of a garment."
collar (v.)youdaoicibaDictYouDict
1550s, "to grab (someone) by the collar or neck," from collar (n.). Meaning "to capture" is attested from 1610s. Related: Collared; collaring. As a past participle adjective, collared "wearing a collar" is from late 14c.