American English vs downward

American English is a noun but downward is not a noun.

Word	Noun	Adjective	Verb	Adverb
American English	Yes	No	No	No
downward	No	Yes	No	Yes

American English (noun)	downward (noun)
the English language as used in the United States

American English (adjective)	downward (adjective)
	extending or moving from a higher to a lower place
	on or toward a surface regarded as a base

American English (adverb)	downward (adverb)
	spatially or metaphorically from a higher to a lower level or position