'angusticlave' originates from Latin, specifically the phrase 'angustus clavus' (plural 'angusti clavi'), where 'angustus' meant 'narrow' and 'clavus' meant 'purple stripe on a tunic'.

'angustus clavus' entered learned English as a direct scholarly borrowing, the elements being compounded into 'angusticlave', which eventually became the modern English word 'angusticlave'.

Initially, it meant the narrow rank stripe (and a tunic bearing it), and this specialized meaning has remained essentially the same in modern usage.