\Blue"back`\, n. (Zo["o]l.)
(a) A trout ({Salmo oquassa}) inhabiting some of the lakes of
    Maine.
(b) A salmon ({Oncorhynchus nerka}) of the Columbia River and
    northward.
(c) An American river herring ({Clupea [ae]stivalis}),
    closely allied to the alewife.