What does Aztecus mean in Latin?

Aztecus, a adjective, means “Aztec”.

How do you pronounce Aztecus?

In classical Latin, [ˈaz.tɛ.kʊs]; in ecclesiastical (church) Latin, [ˈad͡z.te.kus].

adjectivefirst/second-declension adjective

Aztecus (feminine Azteca, neuter Aztecum)

Classical[ˈaz.tɛ.kʊs]Ecclesiastical[ˈad͡z.te.kus]

singular
form	masculine	feminine	neuter
nominative	Aztecus	Azteca	Aztecum
genitive	Aztecī	Aztecae	Aztecī
dative	Aztecō	Aztecae	Aztecō
accusative	Aztecum	Aztecam	Aztecum
ablative	Aztecō	Aztecā	Aztecō
vocative	Aztece	Azteca	Aztecum

plural
form	masculine	feminine	neuter
nominative	Aztecī	Aztecae	Azteca
genitive	Aztecōrum	Aztecārum	Aztecōrum
dative	Aztecīs	Aztecīs	Aztecīs
accusative	Aztecōs	Aztecās	Azteca
ablative	Aztecīs	Aztecīs	Aztecīs
vocative	Aztecī	Aztecae	Azteca

From Spanish azteca.