'registrant' originates from the Latin word 'registrare,' where 'reg-' meant 'rule' and 'strāre' meant 'to write.'

'registrare' transformed into the French word 'registrer,' and eventually became the modern English word 'register' through Middle English.

Initially, it meant 'to record or write down,' but over time it evolved into its current meaning of 'a person who registers.'