1The tail coverts of a peacock collectively, which the bird is able to erect and expand like a fan behind its body.
historical An iridescent or multicoloured stage in the preparation of the philosopher's stone.
3The seaweed Padina pavonia, which has broadly fan-shaped fronds marked with fringed bands in shades of brown and green.
Early 16th century. From the genitive of peacock + tail.