flour: [13] Etymologically, flour is the same word as flower. It originally meant the ‘flower’, or ‘finest part’, of ground grain, and hence eventually just ‘ground (and more or less sifted) grain’. The distinction in spelling between flour and flower did not emerge until the late 18th century, and the spelling flower for ‘flour’ persisted into the early 19th century. => flower[flour etymology, flour origin, 英语词源]