poliosis
/ˌpɒlɪˈəʊsɪs/Medicine
noun
Partial or general greyness or whiteness of the hair, especially if premature; specifically the presence of a circumscribed area of white hair in the scalp (a white forelock).
Origin
Early 19th century; earliest use found in John Mason Good (1764–1827), physician and surgeon. From post-classical Latin poliosis from ancient Greek πολιός grey + post-classical Latin -osis.