IPA: /ˈhɔːntɪŋli/
KK: /ˈhɔːntɪŋli/
In a way that evokes strong feelings of sadness or nostalgia, often in a beautiful or eerie manner.
The music played hauntingly, filling the room with a sense of longing.
Hauntingly → It is formed from "haunt" (from Old French *hanter*, meaning to frequent or visit) and "-ingly" (a suffix used to form adverbs). The word "hauntingly" describes something done in a manner that frequently visits the mind, often in a ghostly or evocative way.
Think of something that 'frequently visits' your thoughts ('haunt') in a way that is memorable or eerie, which is what 'hauntingly' conveys.