-idão

From Old Galician-Portuguese -idõe, from Latin -(i)tūdinem. Doublet of -itude.

-idão f (noun-forming suffix, usually uncountable, plural -idões)

1. -itude; -ness (forms abstract nouns, from adjectives, indicating a state or condition)

   Synonyms: -idade, -eza, -ez, -itude

   ‎grato (“grateful”) + ‎-idão → ‎gratidão (“gratitude”)

   ‎pronto (“ready”) + ‎-idão → ‎prontidão (“readiness”)