'alidada' originates from Arabic, specifically the word 'al-ʿiḍāda', where 'al-' meant 'the' and 'ʿiḍāda' meant 'arm' or 'ruler'.

'al-ʿiḍāda' transformed into the medieval Latin word 'alidada', and eventually became the modern English word 'alidada'.

Initially, it meant 'arm or ruler', but over time it evolved into its current meaning of 'a device for sighting or measuring angles'.