A dictionary of color combinations is a reference book that provides a comprehensive collection of color palettes, along with their corresponding hex codes, RGB values, and other relevant information. These books are a valuable resource for designers, artists, and anyone looking for inspiration for their color schemes.

The book "A Dictionary of Color Combinations" is a well-known reference book that features a vast collection of color combinations. The book is divided into volumes, with Volume 1 being a popular choice among designers.