'arsacid' originates in classical scholarship from Greek and Latin forms referring to the dynasty of Arsaces; ultimately it derives from Parthian/Old Iranian 'Aršaka', the proper name of the dynasty's founder (Arsaces).

'Aršaka' (Parthian/Old Iranian) was rendered in Greek as 'Arsákēs' and 'Arsakidēs' (Ἀρσακίδης), in Latin as 'Arsaces'/'Arsacidae', and later entered English via Latin and modern scholarly usage as 'arsacid'.

Initially it meant 'of or descended from Arsaces' (a dynastic designation). In modern English it is used as a historical term for members of that dynasty or things relating to that dynasty.