'invigilator' originates from Latin, specifically the verb 'invigilare', where the prefix 'in-' meant 'in/against' (intensive) and 'vigilare' meant 'to be watchful'.

'invigilare' (Latin) was adopted into English as the verb 'invigilate' in the 19th century, and the agent noun form 'invigilator' developed from that verb; the modern plural form is 'invigilators'.

Initially related broadly to 'being watchful' or 'keeping vigil,' it became specialized in English to mean 'to supervise examinations,' and hence 'invigilator' now commonly means an exam supervisor.