Engagement is a promise to marry. It is customary on the planet earth, particularly with humans, but it is also possibly practiced among other intelligent species on earth, such as Trolls and the Volti. Often times an engagement involves an engagement party.
J. Mortimer Hutchinson attempted to throw an engagement party for his daughter, Amanda Hutchinson, who was going to marry a young man. His first attempt was foiled by Doctor Pelagian, who caused it to rain oil at his estate.