low-key
adjectiveUK /ˌləʊˈkiː/
US /ˌloʊˈkiː/
Not loud or fancy; calm and simple.
We had a low-key birthday party at home with just a few friends.
OTHER MEANINGS
2. Keeping something secret or not wanting people to notice it.
He kept his plans low-key so no one would make a fuss.
3. In a quiet or gentle way.
She low-key told me the news so nobody else would hear.
4. Slang: slightly or secretly, used to soften what you say.
I'm low-key excited about the school trip.