Meanings of prevailing language in English

Children of various races attend and the prevailing language spoken is Cantonese.

West of it the prevailing language was Latin, and the higher classes of society modelled themselves upon the Italian aristocracy.

There were many coffee-houses, filled with smokers, nearly all of whom accosted us in Turkish, though Arabic is the prevailing language here.

Pushtu, however, is the prevailing language, though it does not seem to be spoken in Herat, or, roughly speaking, west of the Helmund.

And yet among them were wits, philosophers, rhetoricians, poets, and satirists, as was to be expected in a city where Greek was the prevailing language.