sir ‧ loin /ˈsɜːlɔɪn $ ˈsɜːr-/ BrE AmE ( also ˌsirloin ˈsteak ) noun [uncountable and countable]
[ Date: 1400-1500 ; Language: Old French ; Origin: surlonge , from sur 'above' + loigne , longe ( ⇨ ↑ loin ) ]
a good-quality piece of ↑ beef which is cut from the lower part of a cow’s back