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pink [pink 词源字典]: pink: English has three distinct words pink. The colour term [18] appears to have come, by a bizarre series of twists, from an early Dutch word meaning ‘small’. This was pinck (source also of the colloquial English pinkie ‘little finger’ [19]). It was used in the phrase pinck oogen, literally ‘small eyes’, hence ‘half-closed eyes’, which was borrowed into English and partially translated as pink eyes.

It has been speculated that this was a name given to a plant of the species Dianthus, which first emerged in the abbreviated form pink in the 16th century. Many of these plants have pale red flowers, and so by the 18th century pink was being used for ‘pale red’. Pink ‘pierce’ [14], now preserved mainly in pinking shears, is probably of Low German origin (Low German has pinken ‘peck’).

And pink (of an engine) ‘make knocking sounds’ [20] is presumably imitative in origin.
[pink etymology, pink origin, 英语词源]
pink (v.): c. 1200, pungde "pierce, stab," later (early 14c.) "make holes in; spur a horse," of uncertain origin; perhaps from a Romanic stem that also yielded French piquer, Spanish picar (see pike (n.2)). Or perhaps from Old English pyngan and directly from Latin pungere "to prick, pierce" (see pungent). Surviving mainly in pinking shears.