fidejussion
fidejussion (fI-di-j[schwa]sh-[schwa]n). [fr. Latin fidejussio] Roman law. An act by which a person becomes an additional security for another. • The act does not remove the principal’s liability but only adds to the surety’s security. Fidejussion was one of the three types of adpromission, and the only type remaining in Justinian’s law. — Also spelled fidejussio; fideiussio. See ADPROMISSION(1). — fidejussionary, adj.