'peligro' originates from Latin, specifically the word 'periculum', where the root meant 'danger, risk'.

'peligro' changed from Old Spanish 'perigo' (also attested as 'peligo') and eventually became the modern Spanish word 'peligro'.

Initially it meant 'danger' in Latin; over time the word maintained this core meaning in Spanish, with related senses like 'risk' or 'hazard' developing in usage.