'Angolan' is formed in English from the country name 'Angola' with the adjectival/national suffix '-an'.

'Angola' entered Portuguese as 'Angola', ultimately from the Kimbundu word 'ngola' (a royal title meaning 'king'); the place-name 'Angola' was adopted into English, and then the English adjective/demonym 'Angolan' was formed.

Initially the root 'ngola' referred to a royal title; over time the place-name 'Angola' came to denote the territory, and 'Angolan' developed to mean 'of or relating to Angola' or 'a person from Angola'.