Instead of thinking of words as “containers” of meaning, we can look at the “roles” they fulfill within the situation described by a sentence. If the situation is a simple event, as in The boy kicked the ball, then the verb describes an action (kick). The noun phrases in the sentence describe the roles of entities, such as people and things, involved in the action. We can identify a small number of semantic roles (also called “thematic roles”) for these noun phrases.