'Aztec' originates from Spanish, specifically the word 'azteca', which in turn comes from Nahuatl 'āztēcah' (plural of 'āztēcatl'), referring to people from 'Āztlān' (the mythical homeland).

'āztēcatl' (Nahuatl) became Spanish 'azteca', and this was adopted into English as 'Aztec'.

Initially, it meant 'a person from Aztlán' or specifically a member of certain Nahua groups; over time it has come to refer broadly to the people, the empire/civilization, and related cultural artifacts.