Quince is the common English short form for a quinceañera celebration. It is pronounced from the Spanish word for fifteen and is widely used in informal conversation and event descriptions.
The shortened term can refer to the party itself, while quinceañera more specifically identifies the girl or young woman celebrating. In practice, speakers may use quince, quinceañera, and fiesta de quince años with some overlap.
Using quince does not change the tradition’s meaning. The event remains a culturally significant fifteenth-birthday celebration that may include a ceremony, formal dress, a court, a waltz, and a reception. The shorter name is simply more convenient, especially in English-language communities.