The end of a book. Colophon was a city of Ionia, the inhabitants of which were such excellent horsemen that they would turn the scale of battle to the side on which they fought; hence, the Greek phrase, To add a colophonian, means “to put a finishing stroke to any matter.” (Strabo.) In the early times of printing, the statement containing the date, place, printer, and edition was given at the end of the book, and was called the colophon. Now called the “imprint.”
“The volume was uninjured ... from title-page to colophon.” —Scott: The Antiquary.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Colophon from Fact Monster: