Old English hordere "treasurer," from hoard (n.). As "one who gathers and keeps a stock of something," c. 1500, from hoard (v.). In the negative/disapproving sense of "morbidly overzealous junk collector" by 1964.
Old English hord "a treasure, valuable stock or store, an accumulation of something for preservation or future use," hence "any mass of things preserved by being deposited together," from Proto-Germanic *huzdam (source also of Old Saxon hord "treasure, hidden or inmost place," Old Norse hodd, German Hort, Gothic huzd "treasure," literally "hidden treasure"), from PIE root *(s)keu- "to cover, conceal."
"to treasure up, collect, and store; amass and deposit for preservation or security or for future use," Old English hordian, from the root of hoard (n.). Cognate with Old High German gihurten, German gehorden, Gothic huzdjan. Related: Hoarded; hoarding.
<a href="https://www.etymonline.com/word/hoarder">Etymology of hoarder by etymonline</a>
Harper, D. (n.d.). Etymology of hoarder. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/hoarder