blue book

See also: bluebook

English

Etymology

The term dates back to the 15th century, when large blue velvet-covered books were used for record-keeping by the Parliament of the United Kingdom.

Noun

blue book (plural blue books)

1. A book of statistics or almanac, usually published by an agency or as a trade publication.
2. Used other than figuratively or idiomatically: see blue,‎ book.