Black Friar vs Blackfriar

Black Friar and Blackfriar both are nouns.

Word	Noun	Adjective	Verb	Adverb
Black Friar	Yes	No	No	No
Blackfriar	Yes	No	No	No

As nouns, Black Friar and Blackfriar are synonyms defined as:

Black Friar and Blackfriar: a Roman Catholic friar wearing the black mantle of the Dominican order

Other synonyms of Black Friar include Dominican, friar preacher.

Black Friar (noun)	Blackfriar (noun)
a Roman Catholic friar wearing the black mantle of the Dominican order	a Roman Catholic friar wearing the black mantle of the Dominican order