TupiPronunciation: /ˈtuːpi/Definition of Tupi noun (plural same or Tupis) 1a member of a group of American Indian peoples living in scattered areas throughout the Amazon valley. 2 [mass noun] any of the languages of the Tupi, which constitute a branch of the Tupi-Guarani language family. adjective relating to the Tupi or their languages. Derivatives Tupian adjective Origin:a local nameTupi in other Oxford dictionaries Definition of Tupi in the US English dictionary