Where does “Igarassu” come from?

Igarassu (Portuguese) comes from Old Tupi ygarusu, from Old Tupi -gûasu, from Proto-Tupi-Guarani *-wat͡ʃu — augmentative suffix.

Ancestry of “Igarassu”, step by step

StepLanguageWordMeaning
1Old Tupiygarusuship
2Old Tupi-gûasucombining form of gûasu; big
3Proto-Tupi-Guarani*-wat͡ʃuaugmentative suffix
Every word from Proto-Tupi-Guarani *-wat͡ʃu →Every word from Old Tupi -gûasu →Every word from Old Tupi ygarusu →