Rime
Etymology
From Old English "hrīm" ("hoarfrost"). It is unrelated to "rhyme" (a spelling coincidence) and much older, tracing to a common Germanic word for frost.
noun · /RYM/
A white deposit of ice formed when supercooled fog or cloud droplets freeze onto surfaces.
What it names
A specific kind of frost — the feathery ice that coats trees in freezing fog — distinct from ordinary frost.
Example
Rime turned every branch on the ridge into white coral.
Related idea
Rime freezes from fog droplets on contact; hoarfrost grows from water vapor as delicate crystals on cold, clear nights.