'phylarch' originates from Greek, specifically the word 'φυλάρχης' (transliterated 'phylárchēs' or 'phylarchos'), where 'phylē' meant 'tribe' and 'archos' (or 'arkhos') meant 'ruler' or 'leader'.

'phylarch' passed into Late Latin/Medieval Latin as 'phylarchus' and from there entered English usage (mainly in historical and scholarly contexts) as 'phylarch'.

Initially it denoted the actual leader or commander of a phyle (a tribal or civic division) in ancient Greece; over time the term came to be used more generally for a tribal chief or local ruler and is now chiefly historical, literary, or used in specialized contexts.