Pluto (n.)

Roman god of the underworld, early 14c., from Latin Pluto, Pluton, from Greek Ploutōn "god of wealth," from ploutos "wealth, riches," probably originally "overflowing," from PIE root *pleu- "to flow." The alternative Greek name or epithet of Hades in his function as the god of wealth (precious metals and gems, coming from beneath the earth, form part of his realm). The planet (since downgraded) was discovered 1930 by U.S. astronomer Clyde W. Tombaugh; Minerva also was suggested as a name for it. The cartoon dog first appeared in Walt Disney's "Moose Hunt," released April 1931.