smelt (n.)
Old English smelt "sardine, small salmon-like sea fish," cognate with Dutch smelt "sand eel," Danish smelt (c. 1600). OED notes that it has a peculiar odor (but doesn't suggest a connection with smell); Klein suggests a connection with the way the fish melts in one's mouth. Century Dictionary speculates it means "smooth" and compares Old English smeolt, smylt "serene, smooth." Watkins says from PIE root *mel- (1) "soft."