Verglas
Etymology
From French "verglas," a compound of "verre" ("glass") and an old word for ice related to "glace." It is literally "glass ice," named for its clear, slick surface.
noun · /VAIR-glah/
A thin, transparent coating of ice on rock or roads, formed by freezing rain or refrozen meltwater.
What it names
The treacherous, near-invisible "black ice" — a precise word climbers and drivers both need.
Example
A film of verglas made the granite ledge lethal.
Related idea
Verglas is a clear, glassy ice sheet; rime is its opaque, feathery cousin, built from frozen fog.