What is "plouto"

In Greek mythology, Plouto (Πλουτώ) or Pluto was a nymph and the mother of Tantalus by Zeus. Her parents were Oceanus and Tethys (thus making Plouto one of the 3000 Oceanids) or Himas, a Lydian that was otherwise unknown. Plouto was said to be married to Tmolus, the stepfather of Tantalus.