Meaning

adjective showing characteristics of age, especially having grey or white hair; -Coleridge

adjective ancient

adjective covered with fine whitish hairs or down

originPossibly from Middle English *hori (suggested by horilocket (“hoary-locked, having hoary locks or curls”)), equivalent to hoar + -y. Alternatively, Middle English horilocket may represent Middle English hor (“hoar, hoary”) + ilocket (“locked”) rather than hori (“hoary”) + locket (“locked”).

Etymology from Wiktionary, CC BY-SA 3.0