Black Friar vs mendicant

Black Friar and mendicant both are nouns.

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

As nouns, mendicant is a hypernym of Black Friar; that is, mendicant is a word with a broader meaning than Black Friar:

Black Friar: a Roman Catholic friar wearing the black mantle of the Dominican order
mendicant: a male member of a religious order that originally relied solely on alms

Other hypernyms of Black Friar include friar.

Black Friar (noun)	mendicant (noun)
a Roman Catholic friar wearing the black mantle of the Dominican order	a pauper who lives by begging
	a male member of a religious order that originally relied solely on alms

Black Friar (adjective)	mendicant (adjective)
	practicing beggary