Tortoiseshell is a cat coat colouring named for its similarity to tortoiseshell material. Like calicoes, tortoiseshell cats are almost exclusively female. Male tortoiseshells are rare and are usually sterile.
Tortoiseshell cats, combine two colors other than white, either closely mixed or in larger patches. The colors are often described as red and black, but the "red" patches can instead be orange, yellow, or cream, and the "black" can instead be chocolate, grey, tabby or blue. Tortoiseshell cats with the tabby pattern as one of their colors are sometimes referred to as torbies or torbie cats.
"Tortoiseshell" is typically reserved for particolored cats with relatively small or no white markings. Those that are predominantly white with tortoiseshell patches are described as tricolor, tortoiseshell-and-white (in the United Kingdom), or calico (in Canada and the United States).
The tortoiseshell cat is known as the money cat in the United States.