1525,
serlyn, from M.Fr.
surlonge, lit. "upper part of the loin," from
sur "over, above" +
longe "loin," from O.Fr.
loigne (see
loin). Eng. spelling with
sir- dates from 17c., supposedly 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, though only the first is chronologically possible.