What is the meaning of Tortoiseshell?

The horny, translucent, mottled covering of the carapace of the hawksbill turtle, used as a veneer etc.

The hawksbill turtle.

A domestic cat (or a rabbit, guinea-pig, etc.) whose fur has black, brown and yellow markings.

Any of several butterflies, mostly of the genera Nymphalis and Aglais that have similar markings.

Made of the covering of carapace of hawksbill turtle.

Having markings resembling covering of carapace of hawksbill turtle.

Source: wiktionary.org