As a Noun: 1. A class of signs in which the direction of the movement of the sign can be reversed or changed from the citation form to show the relationship between two people or things and the action of the verb. English = directional verb. As a Verb or Adjective: 1. Of a sign, to belong to a class of signs in which the direction of the movement of the sign can be reversed or changed from the citation form to show the relationship between two people or things and the action of the verb. English = (be) directional.