noun
calico cat; tortoiseshell-and-white cat
A domestic cat with a tri-color coat of white, orange, and black (or their dilute versions). In Japanese, 三毛猫 specifically refers to the calico pattern, which is almost always female due to genetics.
うちの三毛猫はとても人懐っこい。
Our calico cat is very friendly.
三毛猫のオスは非常に珍しい。
Male calico cats are extremely rare.
白猫 is a solid white cat, whereas 三毛猫 has a tri-color pattern.
From 三毛 (みけ, 'three fur colors') + 猫 (ねこ, 'cat'). The term directly describes the cat's tri-color coat.