the.com/fog bank

means A distinct, often dense mass of fog with visible edges, typically drifting over or sitting on a body of water.

from 'Fog' is old and murky in its own right — likely from a Scandinavian source related to Danish 'sog' (marsh) or Norwegian dialect 'fogg' (long grass, or spongy ground), surfacing in English around the late 1500s to name both thick mist and, oddly, decaying moss — a word that's been damp in meaning from the start. 'Bank' comes from the Germanic root for a shelf or ridge, the same one that gives us riverbanks and sandbanks — any raised, massed accumulation. Pair them and you get exactly that: fog piled up like a landform, solid enough on the horizon to look like something you could run aground on.