Jactitation Definition: A false boast designed to increase standing at the expense of another. Related Terms: Slander of Title A false boast designed to increase standing at the expense of another. This used to form the basis of an ancient legal petition called "jactitation of marriage" wherein a person could be ordered by the courts to cease claims of being married to a certain person when, in fact, they were not married. The tort of slander of title is a form of jactitation. Categories & Topics: Ancient Common Law Dictionary Family Law Dictionary Find you are constantly looking up definitions? Try our search provider (works in most modern browsers) If you find an error or omission in Duhaime's Legal Dictionary, or if you have legal term suggestion, we'd love to hear from you!