'evening wear' is translated 'des habits de soirée' in French for the formal clothes you wear in cocktails or celebrations.
To say 'good evening' in French you say 'bonsoir'. This is pronounced as 'bon swor'.
ce soir
bonsoir
Samedi soir
soir or nuit
In the evening, same use as good evening or good night in english
"Bonsoir" in French means "good evening." It is a common greeting used to wish someone a pleasant evening or to say hello in the evening.
"Un soir pluvieuse"
bonsoir chacun
Bonsoir, monsieur.
"bonsoir mon amour"
Passez une merveilleuse soirée