Sewellel \Se*wel"lel\, n. [Of American Indian origin.]

(Zo["o]l.) A peculiar gregarious burrowing rodent (Haplodon rufus), native of the coast region of the Northwestern United States. It somewhat resembles a muskrat or marmot, but has only a rudimentary tail. Its head is broad, its eyes are small and its fur is brownish above, gray beneath. It constitutes the family Haplodontid[ae]. Called also boomer, showt'l, and mountain beaver.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Boomer \Boom"er\, n.

1. One who, or that which, booms.

2. (Zo["o]l.) A North American rodent, so named because it is said to make a booming noise. See Sewellel.

3. (Zo["o]l.) A large male kangaroo.

4. One who works up a ``boom''. [Slang, U. S.]

Source: Webster's Revised Unabridged Dictionary (1913)