low-key
adjectiveUK /ˌləʊ ˈkiː/
US /ˌloʊ ˈkiː/
Quiet and not trying to get a lot of attention.
They had a low-key birthday party at home with just family.
OTHER MEANINGS
2. Not bright or strong in color or light.
The room was painted in low-key gray and blue tones.
3. Keeping something secret or not talking about it openly.
He kept his plans low-key until everything was ready.
4. In a quiet or gentle way, as an adverb in informal speech.
She low-key hoped it would rain so the game would be canceled.