war vs Mexican-American War

war and Mexican-American War both are nouns.

Word	Noun	Adjective	Verb	Adverb
war	Yes	No	Yes	No
Mexican-American War	Yes	No	No	No

war (noun)	Mexican-American War (noun)
the waging of armed conflict against an enemy	after disputes over Texas lands that were settled by Mexicans the United States declared war on Mexico in 1846 and by treaty in 1848 took Texas and California and Arizona and New Mexico and Nevada and Utah and part of Colorado and paid Mexico $15,000,000
a concerted campaign to end something that is injurious
an active struggle between competing entities
a legal state created by a declaration of war and ended by official declaration during which the international rules of war apply

war (verb)	Mexican-American War (verb)
make or wage war