Late Middle English; earliest use found in John Trevisa (c1342–?1402), translator. Alteration of bloman, with substitution of blue for the first element.
Definition of blue man in US English:
blue man
nounˈbluː ˌman
historical
A black man; an African; = "bloman".
Origin
Late Middle English; earliest use found in John Trevisa (c1342–?1402), translator. Alteration of bloman, with substitution of blue for the first element.