Dictionary of Idioms
by Christine Ammer
This dictionary was recommended to us because it frequently explains how and when the idiom originated. The inclusion of the idioms history transforms the entries from informative to facinating.
From the publisher:
Bite the bullet, get on the stick, make no bones about, take the cake. The cat will never have your tongue once you have The American Heritage Dictionary of Idioms - the largest collection of idioms and popular phrases available today. Its main fare is idioms - groups of two or more words that taken together mean something different from the literal meaning of the individual words.
Each entry is defined and has an example sentence showing the idiom used in context. Most entries offer an explanation of the idiom's literal meaning or origin and include information about its first appearance in English.
Produced in consultation with the editors of The American Heritage Dictionary of the English Language, Third Edition, this book is a storehouse of fascinating and useful information.