- Any of several baleen whales of the family Balaenopteridae having longitudinal grooves on the throat and a small, pointed dorsal fin, and including the blue whale and the humpback whale.
- A finner-whale of the genus <em>Balænoptera</em>, having short flippers, a dorsal fin, and the throat plicated.
- A very large North Atlantic whalebone whale (<spn>Physalus antiquorum</spn>, or <spn>Balænoptera physalus</spn>). It has a dorsal fin, and strong longitudinal folds on the throat and belly. Called also <altname>razorback</altname>.
- Any <xref>whale</xref> with <xref>longitudinal</xref> skin folds running from below the mouth to the <xref>navel</xref>, allowing the capacity of the mouth to expand greatly when feeding.
- any of several baleen whales of the family Balaenopteridae having longitudinal grooves on the throat and a small pointed dorsal fin