fetus vs American spelling

fetus and American spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
fetus	Yes	No	No	No
American spelling	Yes	No	No	No

fetus (noun)	American spelling (noun)
an unborn or unhatched vertebrate in the later stages of development showing the main recognizable features of the mature animal	English orthography used in the United States (characterized by 'analyze', 'center', 'usable')