fetal membrane vs veil

fetal membrane and veil both are nouns.

Word	Noun	Adjective	Verb	Adverb
fetal membrane	Yes	No	No	No
veil	Yes	No	Yes	No

As nouns, veil is a hyponym of fetal membrane; that is, veil is a word with a more specific, narrower meaning than fetal membrane:

fetal membrane: any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetus
veil: the inner membrane of embryos in higher vertebrates (especially when covering the head at birth)

Other hyponyms of fetal membrane include allantois, caul, embryonic membrane, umbilical, umbilical cord.

fetal membrane (noun)	veil (noun)
any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetus	a garment that covers the head and face
	a vestment worn by a priest at High Mass in the Roman Catholic Church; a silk shawl
	the inner membrane of embryos in higher vertebrates (especially when covering the head at birth)
	a membranous covering attached to the immature fruiting body of certain mushrooms

fetal membrane (verb)	veil (verb)
	make undecipherable or imperceptible by obscuring or concealing
	to obscure, or conceal with or as if with a veil