fibrocartilage vs gristle

fibrocartilage and gristle both are nouns.

Word	Noun	Adjective	Verb	Adverb
fibrocartilage	Yes	No	No	No
gristle	Yes	No	No	No

As nouns, gristle is a hypernym of fibrocartilage; that is, gristle is a word with a broader meaning than fibrocartilage:

fibrocartilage: cartilage that is largely composed of fibers like those in ordinary connective tissue
gristle: tough elastic tissue; mostly converted to bone in adults

Other hypernyms of fibrocartilage include cartilage.

fibrocartilage (noun)	gristle (noun)
cartilage that is largely composed of fibers like those in ordinary connective tissue	tough elastic tissue; mostly converted to bone in adults