A western party is a themed event that typically involves dressing up in cowboy or cowgirl attire, playing country music, and eating traditional western food. The term 'POSSE' is a five-letter word often used to describe a group of people who have come together for a common purpose, such as a search party or a group of law enforcement officers. In the context of a western party, a POSSE could refer to the group of people attending the event.