They are usually called 'fleabitten greys
Roan
certainly not, there is speckled hen, white horse. And Lots More.
Yes, speckled can be an adjective--a speckled egg.
A purple roan horse has a unique coat color that combines shades of purple and white hairs, creating a speckled or mottled appearance. This coloration is rare and distinct, making the horse easily recognizable.
"Speckled" has two syllables.
a speckled rock
Speckled moray was created in 1932.
Speckled Bird was created in 1993.
Speckled Wood was created in 1758.
Speckled Warbler was created in 1801.
Speckled Tanager was created in 1850.
Speckled catshark was created in 1972.