'magus' originates from Latin, specifically the word 'magus', where Latin borrowed it from Greek 'μάγος' ('magos'), ultimately from Old Persian 'maguš' meaning 'member of a priestly caste'.

'magus' passed from Old Persian 'maguš' into Greek as 'μάγος' ('magos'), then into Latin as 'magus', entered Middle English from Latin and Old French forms, and eventually became the modern English word 'magus'.

Initially, it meant 'member of a priestly caste' in Old Persian, but over time it evolved into meanings such as 'wise man' and 'magician' (a person with magical or occult knowledge).