Agent (grammar)

In linguistics, a grammatical agent is the thematic relation of the cause or initiator to an event. The agent is a semantic concept distinct from the subject of a sentence as well as from the topic. While the subject is determined syntactically, primarily through word order, the agent is determined through its relationship to the action expressed by the verb. For example, in the sentence "The little girl was bitten by the dog", girl is the subject, but dog is the agent.

The word agent comes from the present participle agens, agentis ('the one doing') of the Latin verb agere, to 'do' or 'make'.