clingyoudaoicibaDictYouDict[cling 词源字典]
cling: [OE] The basic underlying sense of cling seems to be ‘stick, adhere’, but surviving records of the word in Old English reveal it only in the more specialized senses ‘congeal’ or ‘shrivel’ (the notion being that loss of moisture causes something to contract upon itself or adhere more closely to a surface). It is not really until the late 13th century that the more familiar ‘adhere’ (as in ‘a wet shirt clinging to someone’s back’) begins to show itself, and no hint that ‘clinging’ is something a human being can do with his or her arms emerges before the early 17th century.

The word goes back to a prehistoric Germanic base *klingg-, whose variant *klengk- is the source of English clench [13] and clinch [16].
=> clench, clinch[cling etymology, cling origin, 英语词源]
cling (v.)youdaoicibaDictYouDict
Old English clingan "hold fast, adhere closely; congeal, shrivel" (strong verb, past tense clang, past participle clungen), from Proto-Germanic *klingg- (cognates: Danish klynge "to cluster;" Old High German klinga "narrow gorge;" Old Norse klengjask "press onward;" Danish klinke, Dutch klinken "to clench;" German Klinke "latch").

The main sense shifted in Middle English to "adhere to" (something else), "stick together." Of persons in embrace, c. 1600. Figuratively (to hopes, outmoded ideas, etc.), from 1580s. Of clothes from 1792. Related: Clung; clinging.