piebald
Concise Oxford English Dictionary © 2008 Oxford University Press:
piebald/ˈpʌɪbɔːld/
▶adjective (of a horse) having irregular patches of two colours, typically black and white. ▶noun a piebald horse.
– origin C16: from pie2 (because of the magpie's black and white plumage) + bald (in the obs. sense ‘streaked with white’).
'piebald' also found in these Oxford entries:

