soirée; evening party; evening performance
Refers to a formal evening social gathering or an evening performance, such as a concert or theater show. The word carries a sophisticated, often cultural connotation.
from French
A soirée will be held at the embassy tonight.
Refers to formal attire worn for evening events. This usage is less common and may be considered somewhat dated or specialized, often encountered in fashion contexts.
オペラのソワレのチケットを予約した。
I booked tickets for the evening opera performance.
She appeared at the party wearing a beautiful evening dress.