truism vs bromide

truism and bromide both are nouns.

Word	Noun	Adjective	Verb	Adverb
truism	Yes	No	No	No
bromide	Yes	No	No	No

As nouns, bromide is a hyponym of truism; that is, bromide is a word with a more specific, narrower meaning than truism:

Other hyponyms of truism include banality, cliche, commonplace, platitude.

truism (noun)	bromide (noun)
an obvious truth	a trite or obvious remark
	any of the salts of hydrobromic acid; formerly used as a sedative but now generally replaced by safer drugs