'fortaleza' originates from Spanish, ultimately tracing back to Latin roots related to strength: Latin 'fortis' meaning 'strong'.

'fortaleza' entered Spanish in the medieval period (Old Spanish 'fortaleza' / 'fortalesa'), influenced by Old French 'forteresse' (meaning 'fortress') and deriving ultimately from Latin 'fortis'. Over time the word stabilized in modern Spanish as 'fortaleza'.

Initially it referred primarily to a physical fortress or fortified place; over time the word also acquired the figurative sense of 'strength' or 'fortitude' (moral or physical).