sullenyoudaoicibaDictYouDict[sullen 词源字典]
sullen: [16] The etymological notion underlying sullen is of being miserable because one is ‘on one’s own’. The word comes from Anglo- Norman *solein ‘alone’, hence ‘miserable’, a derivative of Old French soul ‘alone’ (source of English sole).
=> sole, solo[sullen etymology, sullen origin, 英语词源]
sullen (adj.)youdaoicibaDictYouDict
1570s, alteration of Middle English soleyn "unique, singular," from Anglo-French *solein, formed on the pattern of Old French solain "lonely," from soul "single," from Latin solus "by oneself, alone" (see sole (adj.)). The sense shift in Middle English from "solitary" to "morose" (i.e. "remaining alone through ill-humor") occurred late 14c. Related: Sullenly; sullenness.