'declaratory' originates from Latin, specifically the Late Latin word 'declaratorius,' where 'de-' meant 'completely/from' and 'clarare' meant 'to make clear.'

'declaratory' changed from Late Latin 'declaratorius' into Old/Anglo-French forms such as 'declaratorie' and then entered Middle English as 'declaratorie', eventually becoming the modern English 'declaratory'.

Initially, it meant 'serving to make clear or to declare,' and over time it has largely retained that sense while becoming more specialized in legal contexts to denote formal declarations or judgments.