sigh (v.)youdaoicibaDictYouDict[sigh 词源字典]
mid-13c., probably a Middle English back-formation from sighte, past tense of Old English sican "to sigh," perhaps echoic of the sound of sighing. Related: Sighed; sighing.[sigh etymology, sigh origin, 英语词源]
sigh (n.)youdaoicibaDictYouDict
early 14c., from sigh (v.).