LATIN DICTIONARYLexicon Latīnum
proper nounthird declension

Bonus Āēr

Bonus Āēr m sg (genitive Bonī Āeris)
Ecclesiastical[ˈbɔː.nus ˈaː.er]

Meaning

  1. New LatinBuenos Aires (the capital city of Argentina)
    Fanum S. Trinitatis de Bono-Aere, Buenos-Aires, erect. 1661.City of the Holy Trinity of Buenos Aires, built in 1661.1682, Michel Antoine Baudrand, “Americæ urbes, ubiSenatus sive sedes juridicæ las Audiencias Reales”, in Geographia ordine litterarum disposita, volume 1, Paris: Stephanum Michalet, page 51, column 2:
  2. New LatinBuenos Aires (the largest and most populous province in Argentina, part of the Pampas region)

Declension

declension
formsingularplural
nominativeBonus Āēr—
genitiveBonī Āeris—
dativeBonō Āerī—
accusativeBonum Āera
Bonum Āerem		—
ablativeBonō Āere—
vocativeBone Āēr—

Origins

Calque of Spanish Buenos Aires.

Quick answers

What does Bonus Āēr mean in Latin?
Bonus Āēr, a proper noun, means “Buenos Aires (the capital city of Argentina); Buenos Aires (the largest and most populous province in Argentina, part of the Pampas region)”.
What is the genitive of Bonus Āēr?
The genitive singular is Bonī Āeris. Bonus Āēr is third declension.