1. small cold-water silvery fish; migrate between salt and fresh water
2. small trout-like silvery marine or freshwater food fishes of cold northern waters
3. Any one of numerous species of small silvery salmonoid fishes of the genus Osmerus and allied genera, which ascend rivers to spawn, and sometimes become landlocked in lakes. They are esteemed as food, and have a peculiar odor and taste.
4. extract (metals) by heating
5. To melt or fuse, as, ore, for the purpose of separating and refining the metal; hence, to reduce; to refine; to flux or scorify; as, to smelt tin.