hoar

nouns

ice crystals forming a white deposit (especially on objects outside)
frost, hoar, hoarfrost, rime

adjectives

showing characteristics of age, especially having grey or white hair
"whose beard with age is hoar"-Coleridge; "nodded his hoary head"
gray, gray-haired, gray-headed, grey, grey-haired, grey-headed, grizzly, hoar, hoary, white-haired