Pluto (n.) Look up Pluto at Dictionary.com
Roman god of the underworld, brother of Zeus and Neptune, from Latin Pluto, Pluton, from Greek Plouton "god of wealth," literally "wealth, riches," probably originally "overflowing," from PIE *pleu- "to flow" (see pluvial). The planet (since downgraded) was discovered 1930 by C.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.