'festivator' originates from Latin, specifically from the adjective 'festivus' and the agentive suffix '-ator', where 'festivus' meant 'of a feast' and '-ator' meant 'one who does (an action)'.

'festivus' in Classical Latin led to medieval/late Latin verbal forms such as 'festivare' (to celebrate); an agentive form with the suffix '-ator' produced Neo-Latin/Medieval-Latin forms like 'festivator', which later entered English as the rare modern usage 'festivator'.

Initially it meant 'relating to a feast or festive'; over time the form came to be used as an agent noun meaning 'one who celebrates or organizes celebrations', the sense now found in English.