'appreciatory' originates from Latin via Late Latin and Old French, specifically from the Late Latin/Vulgar Latin word 'appretiare' (from Latin 'ad' + 'pretium'), where 'ad-' meant 'to/toward' and 'pretium' meant 'price, value'.

'appreciatory' changed from Late Latin 'appretiare' into Old French 'aprecier' (to value, esteem), entered Middle English as 'appreciate' (verb), and the adjective form developed with the suffix '-ory' to become the modern English 'appreciatory'.

Initially it had senses related to 'setting a price' or 'valuing' (estimating worth), but over time it evolved into the modern sense of 'showing appreciation, praise, or gratitude'.