hair [OE] In English the state of people’s hair is used to reflect how they feel and behave—since the 1980s if you have a bad hair day you have a day when everything seems to go wrong. If you don’t turn a hair you are unflustered. It was first used in the early 19th century of horses who did not show any signs of sweating, which would curl and roughen their coat. If you let your hair down you become uninhibited. This idea started in the mid 19th century as to let down the back hair, with the notion of relaxing and becoming less formal. The expression the hair of the dog [M16th], for a hangover cure, is a shortening of a hair of the dog that bit you. It comes from an old belief that someone bitten by a rabid dog could be cured of rabies by taking a potion containing some of the dog’s hair. Harsh [ME] comes from the related Middle Low German harsch ‘rough’, the literal meaning of which was ‘hairy’, from haer ‘hair’.