Agent is the semantic concept which is related both to subject and topic of the sentence but may be distinct from them. It has no clear scientific definition but usually easy to determine from meaning. Agent is one of arguments of verb (while another one called patient), the initiator, cause, source or “doer” of an action expressed by predicate. In majority of Indo-European languages agent matches the subject of the sentence in active voice ¹⁾. However, in passive voice agent is traditionally treated as the object of sentence ²⁾. The concept of agent is very useful in describing grammar of ergative languages. Archaic Nûrlâm was the ergative language where sentence “” ³⁾ translates into “” instead of “” as in Standard and Modern Nûrlâm.