In linguistics, a grammatical agent is a thematic relation that refers to the cause or initiator of an event. The agent is a semantic concept distinct from the subject of a sentence. While the subject is determined syntactically, primarily through word order, the agent is determined through its relationship to the action expressed by the verb. The word comes from the present participle agens, agentis ("the one doing") of the Latin verb agere, to "do" or "make".