sirloinyoudaoicibaDictYouDict[sirloin 词源字典]
sirloin: [16] One of the oldest of etymological chestnuts is that sirloin got its name because a particular English king found the joint of beef so excellent that he knighted it. The monarch in question has been variously identified as Henry VIII, James I, and Charles II, but while the first of these is chronologically possible, in fact the story has no truth in it at all. The more sober facts are that the word was borrowed from Old French *surloigne, a compound formed from sur ‘above’ and loigne ‘loin’ (source of English loin). The spelling sir- (first recorded in the 18th century) no doubt owes something to the ‘knighting’ story.
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sirloin (n.)youdaoicibaDictYouDict
early 15c., surloine, from Middle French surlonge, literally "upper part of the loin," from sur "over, above" (see sur-) + longe "loin," from Old French loigne (see loin).

English spelling with sir- dates from 1620s, by folk-etymology supposed to be because the cut of beef was "knighted" by an English king for its superiority, a tale variously told of Henry VIII, James I, and Charles II. The story dates to 1655.