köken: Borrowed from English rime, from Middle English rim, rime, rym, ryme (“hoar frost; rime”), from Old English hrīm (“frost”), from Proto-West Germanic *hrīm (“rime; hoar frost”), from Proto-Germanic *hrīmą (North Germanic), *hrīmaz, *hrīmô, probably from Proto-Indo-European *krey- (“to graze, touch; to streak”).
köken: Inherited from Proto-Slavic *seržь (expected would be **среж), possibly merged with *skręga (“curtailment”) (whence Russian скря́га (skrjága, “cheapskate”)).
frost (thin ice crystals that form on plant leaves, twigs, or also on wires, cables, etc. when the air temperature is below the freezing point) · gray hair, graying hair
From Proto-Balto-Slavic *śer(s)nos, from a Proto-Indo-European *ḱer(s)-no- (“frozen water”). Cognate with Latvian sȩ̄rsna (“hoarfrost”), Proto-Slavic *sẽrnъ (“id”), Old Armenian սառն (saṙn, “ice”), Proto-Germanic *herzną (“frozen snow”). The adjectival sense is an extension of the "frozen crust" sense.