Achaemenid
noun
Achae·me·nid ə-ˈkē-mə-nəd 
plural Achaemenids also Achaemenidae ˌa-kə-ˈme-nə-ˌdē
: a member of the ruling house of ancient Persia generally considered historically important from the assumption of power by Cyrus the Great (559 b.c.) to the overthrow of Darius III (330 b.c.)
Word History
Etymology
borrowed from Latin Achaemenidēs, borrowed from Greek Achaimenídēs, from Achaiménēs (Achaemenes), alleged founder of the dynasty (borrowed from Old Persian Haxāmaniš) + -idēs -id entry 1
First Known Use
1889, in the meaning defined above