'hoarder' originates from Old English, specifically the word 'hord', where 'hord' meant 'treasure, store, hoard'.

'hoard' (from Old English 'hord') passed into Middle English as 'horde'/'hurd' and later developed into the noun 'hoard' and the agent-form 'hoarder' in Modern English.

Initially it referred to a 'store' or 'treasure' (the thing stored); over time the sense extended to the action of hiding or storing things and then to a person who stores or accumulates things—'hoarder'—often with a negative or compulsive nuance.