boto

noun

bo·​to ˈbō-ˌtü 

variants or less commonly bouto

plural botos also boutos

: a large, heavy river dolphin (Inia geoffrensis) native to the Amazon and Orinoco river basins that is dark gray when young and pinkish as an adult

The boto—the largest of the four remaining species of river dolphin—is well adapted to its murky environment. Unfused vertebrae in its neck mean it is capable of turning its head through a range of 180 degrees, allowing it to squeeze around submerged trees and roots.

—Rowan Hooper, New Scientist, 17 Dec. 2011

called also Amazon dolphin, Amazon river dolphin, pink dolphin, pink river dolphin

Word History

Etymology

borrowed from Brazilian Portuguese boto, perhaps from regional Portuguese, "wineskin," going back to Late Latin buttis "cask"; from its shape

First Known Use

1875, in the meaning defined above

The Ultimate Dictionary Awaits

Expand your vocabulary and dive deeper into language with Merriam-Webster Unabridged.

1. Expanded definitions
2. Detailed etymologies
3. Advanced search tools
4. All ad-free

Discover what makes Merriam-Webster Unabridged the essential choice for true word lovers.

Start Your Free Trial Now