gum ridge vs appendage

gum ridge and appendage both are nouns.

Word	Noun	Adjective	Verb	Adverb
gum ridge	Yes	No	No	No
appendage	Yes	No	No	No

As nouns, appendage is a hypernym of gum ridge; that is, appendage is a word with a broader meaning than gum ridge:

gum ridge: a ridge that forms the borders of the upper and lower jaws and contains the sockets of the teeth
appendage: a natural prolongation or projection from a part of an organism either animal or plant

Other hypernyms of gum ridge include outgrowth, process.

gum ridge (noun)	appendage (noun)
a ridge that forms the borders of the upper and lower jaws and contains the sockets of the teeth	a part that is joined to something larger
	an external body part that projects from the body
	a natural prolongation or projection from a part of an organism either animal or plant