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.