In early France, sportsmen experimented with different dog breeds for hunting game. They developed a hound whose deep bark they called abai, from the Latin "to open the mouth." The dog was trained to run down big game and bark continuously. When the term reached England, it was modified to "bay." A stag run to exhaustion and trapped was said to be "held at bay."
As early as the 13th century, the expression was used figuratively to mean any method of putting someone at a standstill.
Today's term for a standard measurement in horse racing originally had nothing to do with horses. A "furrow-long" comes from farming in the Middle Ages, and means "as long as a furrow in a plowed field." But how long is a furrow? Forty poles. A pole is the width between 2 furrows, or 5-1/2 yards. A legal acre was 40 poles long and 4 poles wide, making the length of a common field just 1/8 of a mile. Although the length of furrows changed over time, a furlong remained 220 yards - and became a standard measurement in the horse-racing business, of all things.
This horse color is referred to several times in the Mother Goose nursery rhymes. But what is it exactly? It probably comes from "apple-gray," say the editors of "Word Mysteries and Histories," referring to the spotty dark-gray markings found on some apples - as well as gray horses. The "d" is the mystery. Dapple-gray first appeared in the 14th century in "The Canterbury Tales." Chaucer used "pomely-gray," an English translation of the French gris-pommele or apple-gray, to describe blotchy apples. Looks as if dapple was simply a corruption of apple.
Imagine a yard full of hens who've just been alerted to a nearby fox and you'll understand the origin of this old-time expression meaning commotion (fuss) and excitement (display of feathers), as in "What a lot of fuss and feathers over a house guest!" Nowadays, feathers has been dropped from this pleasing alliteration.
SOURCES: 'Dictionary of Word Origins,' by Joseph Shipley; 'The Oxford Dictionary of English Etymology,' by Charles Onions; 'Etymological Dictionary of the English Language,' by Walter Skeat; 'The Encyclopedia of Word and Phrase Origins,' by Robert Hendrickson; 'Why You Say It,' by Webb Garrison.