n. A Mohammedan sovereign: as, the Sultan of Zanzibar or of Morocco; by way of eminence, the ruler of Turkey, who assumes the title of Sultan of sultans; in old use, any ruler.n. In ornithology, a purple or hyacinthine gallinule, or porphyrio; a bird of either of the genera Porphyrio and Ionornis, belonging to the rail family, Rallidæ: so called from their gorgeous coloration. The American sultan is Ionornis martinica. See the generic names, and gallinule. Also called sultana.n. An ornamental variety of the domestic hen, of small size and pure-white plumage, and having the head heavily crested and bearded, beak white, legs blue, shanks feathered, and toes five.n. Either of two garden-flowers, Centaurea moschata, the sweet sultan, with purple or white flowers, and C. suaveolens, the yellow sultan: both often classed as Amberboa.