waistband vs cummerbund

waistband and cummerbund both are nouns.

Word	Noun	Adjective	Verb	Adverb
waistband	Yes	No	No	No
cummerbund	Yes	No	No	No

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

waistband: a band of material around the waist that strengthens a skirt or trousers
cummerbund: a broad pleated sash worn as formal dress with a tuxedo

waistband (noun)	cummerbund (noun)
a band of material around the waist that strengthens a skirt or trousers	a broad pleated sash worn as formal dress with a tuxedo