A soiree is an elegant evening gathering, usually at someone's home. The jeans and t-shirt you wear to a regular party won't cut it — a soiree requires far fancier attire.
Soiree, pronounced "swah-RAY," is a French word. Soir means "evening" in French, and soiree is literally an "evening party." But this is no Super Bowl party with potato chips and people slouching in easy chairs — a soiree is an elegant affair. Though often held in someone's house, people dress up. There may be music provided by a classical pianist or a jazz combo and fancy food.