Hoary means white with age, or very old and stale. A hoary beard, a hoary old joke, hoary with frost.
The physical sense is white or grey with age or with frost, and hoarfrost is the same word. The figurative sense has almost taken over: a hoary joke is one everybody has heard, and hoary is nearly always dismissive when applied to ideas.
1adjectivehoaryWhite with age, or very old and stale.
“The hoary old man leaned on his stick, his beard and hair as white as frost.”
hoary is a quality of age.
From hoar, Old English har, grey or venerable, plus -y. Hoarfrost is the white coating that looks like grey hair.
Middle English
*hori
English, today
hoary
Built from
Possibly from Middle English hori (suggested by horilocket (“hoary-locked, having hoary locks or curls”)), equivalent to hoar + y. Alternatively, horilocket may represent hor (“hoar, hoary”) + ilocket (“locked”) rather than hori (“hoary”) + locket (“locked”).
Etymology from Wiktionary, CC BY-SA