lingerie vs nightdress

lingerie and nightdress both are nouns.

Word	Noun	Adjective	Verb	Adverb
lingerie	Yes	No	No	No
nightdress	Yes	No	No	No

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

lingerie: women's underwear and nightclothes
nightdress: lingerie consisting of a loose dress designed to be worn in bed by women

Other hyponyms of lingerie include gown, night-robe, nightgown, nightie, undies.

lingerie (noun)	nightdress (noun)
women's underwear and nightclothes	lingerie consisting of a loose dress designed to be worn in bed by women