A very unique multicolored fur pattern for domestic cats, it combines black fur with orange/yellow fur mixed very closely, creating a color pattern similar to a tortoise's shell.
Almost all tortoiseshell cats are female as it is a condition effected by genetics, while this coat genetic phenotype can happen to any other fur color combinations, typically only the cats mostly with black/orange color coats are referred to as tortoiseshells. Some torties have a 'split-face' pattern as depicted in post #6879810.
See also
Calico cat (also known as tortoiseshell-and-white)
