IPA: /ˌʌndərˈsteɪtɪdli/
KK: /ʌndərˈsteɪtɪdli/
In a manner that is subtle and not overly showy or elaborate.
She dressed understatedly for the event, choosing simple colors and minimal accessories.
Understatedly → It is formed from "under-" (meaning below or beneath) and "state" (from Latin "stare", meaning to stand) combined with the adverbial suffix "-ly" (meaning in a manner of). The word "understatedly" means in a manner that is presented with restraint or modesty, standing below the level of what might be expected.
Think of presenting something in a way that is 'below' ('under-') what is typically expected, as if it is 'standing' ('stare') back modestly.