hoar ‧ y /ˈhɔːri/ BrE AmE adjective
[ Date: 1500-1600 ; Origin: hoar ; ⇨ ↑ hoarfrost ]
1 . [usually before noun] a hoary joke, remark etc is so well known that people no longer find it amusing or interesting:
Not that hoary old chestnut (=old idea, joke, remark etc) again.
2 . old-fashioned grey or white in colour, especially through age