Sulphur-bottom \Sul`phur-bot"tom\, n. (Zool.) A very large whalebone whale of the genus Sibbaldius, having a yellowish belly; especially, Sibbaldius sulfureus of the North Pacific, and Sibbaldius borealis of the North Atlantic; -- called also sulphur whale. [1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

Sulphur-bottom \Sul`phur-bot"tom\, n. (Zo["o]l.) A very large whalebone whale of the genus Sibbaldius, having a yellowish belly; especially, S. sulfureus of the North Pacific, and S. borealis of the North Atlantic; -- called also sulphur whale.

Source: Webster's Revised Unabridged Dictionary (1913)