(n.) a snow-covered hill [Scots]
A snow-topped or snow-covered hill is a snaw-breist—or at least it is according to the Scottish National Dictionary, as well as several other older dictionaries of dialectal and regional English.
Unsurprisingly, snaw is just a regional form of snow. So in Scots, as well as being snaw-blind and throwing snawballs, you can dust off snawpattens (clumps of snow that adhere to the soles of shoes), dodge a snaw-shurl (a raft of snow falling from the roof of a house), and try to keep your balance on a snaw-rink (a slippery, partially frozen patch of snow).
Breist here is the Scots word for ‘breast’—a somewhat unsubtle reference to the rolling tops of hills. But use of this word in a figurative context like this is by no means unique, and breast is commonly used in English as a term for any similarly shaped or positioned structure, or for the frontmost or most projecting part of something.
So, as well as the obvious, in English a breast can be the topmost part of a dam; the surface of an area of water; the front part of a plough; a coalface in a mine; and, in its most obvious metaphorical use, the projecting brick structure forming a hearth or ‘chimney-breast’. In Scots, likewise, breist is used to mean a stone slipway projecting from a coastline; the frontmost board or spar of a wooden cart; and, perhaps less appealingly, a layer in a manure heap.