This book is a comprehensive survey of the idioms currently used in American English. An idiom is a set phrase of two or more words that means something different from the literal meaning of the individual words. For instance, the phrase to change one's tune has nothing to do with music but means "to alter one's attitude." Similarly, to hit the nail on the head often has nothing to do with carpentry but means simply "to be absolutely right." Idioms are the idiosyncrasies of a language. Often defying the rules of logic, they pose great difficulties for non-native speakers.