neckyoudaoicibaDictYouDict[neck 词源字典]
neck: [OE] Neck originally meant only the ‘back or nape of the neck’ (that is what its modern German relative nacken denotes, and in Old English times the usual word for ‘neck’ in general was heals). It seems to go back to a prehistoric Indo-European base *knoksignifying ‘high point, ridge’, which also produced Irish cnoc ‘hill’. The use of the verb neck for ‘kiss and cuddle’ dates back at least to the early 19th century.
[neck etymology, neck origin, 英语词源]
neck (n.)youdaoicibaDictYouDict
Old English hnecca "neck, nape, back of the neck" (a fairly rare word) from Proto-Germanic *hnekk- "the nape of the neck" (cognates: Old Frisian hnekka, Middle Dutch necke, Dutch nek, Old Norse hnakkr, Old High German hnach, German Nacken "neck"), with no certain cognates outside Germanic, though Klein's sources suggest PIE *knok- "high point, ridge" (source of Old Irish cnocc, Welsh cnwch, Old Breton cnoch "hill").

The more usual Old English words were hals (the general Germanic word, cognate with Gothic, Old Norse, Danish, Swedish, Dutch, German hals), cognate with Latin collum (see collar (n.)); and sweora, swira "neck, nape," probably also from a PIE root meaning "column" (cognate with Old English swer "column," Sanskrit svaru- "post").

Transferred senses attested from c. 1400. Phrase neck of the woods (American English) is attested from 1780 in the sense of "narrow stretch of woods;" 1839 with meaning "settlement in a wooded region." To stick one's neck out "take a risk" is first recorded 1919, American English. Horses running neck and neck is attested from 1799.
neck (v.)youdaoicibaDictYouDict
"to kiss, embrace, caress," 1825 (implied in necking) in northern England dialect, from neck (n.). Compare Middle English halsen "to embrace or caress affectionately, to fondle sexually," from hals (n.) "neck." Earlier, neck as a verb meant "to kill by a strike on the neck" (mid-15c.). Related: Necked.