Arsacidae

Part of speech: noun

Definitions

1. The ruling family of the ancient Parthian Empire in Iran and Mesopotamia, who held power from about 247 BCE to 224 CE
2. Royal line of Parthian monarchs descended from Arsaces, the founder of the Parthian state in Central Asia and Persia
3. The dynasty of rulers who governed Parthia for roughly four centuries, named after their legendary founder Arsaces

Etymology: Arsacidae was the name of the dynasty that ruled Parthia, a kingdom east of the Tigris that at its height stretched across much of Iran and Mesopotamia. The dynasty took its name from its founder, Arsaces, a figure whose name survives in Greek and Latin sources. The Latin form "Arsacidae" is the plural of "Arsacidēs", meaning "descendants of Arsaces", so the word literally means "the sons of Arsaces" or "the house of Arsaces". English borrowed the term directly from Latin, so it keeps the Latin plural ending rather than adapting to English patterns. Speakers use it almost exclusively in historical writing about Parthia, where it names the line of kings as a group rather than any single ruler. Its form, with the "-idae" ending, follows the same pattern as family-group names in Latin and Greek, which is why it sounds more like a Latin scientific label than an everyday English noun.