What does Cenimagnī mean in Latin?

Cenimagnī, a proper noun, means “A Celtic tribe of Britannia, mentioned by Julius Caesar.”.

What is the genitive of Cenimagnī?

The genitive singular is Cenimagnōrum. Cenimagnī is masculine, second declension.

In classical Latin, [kɛ.nɪˈmaŋ.niː]; in ecclesiastical (church) Latin, [t͡ʃe.niˈmaɲ.ɲi].

proper noun · masculinesecond declension

Cenimagnī m pl (genitive Cenimagnōrum)

Classical[kɛ.nɪˈmaŋ.niː]Ecclesiastical[t͡ʃe.niˈmaɲ.ɲi]

A Celtic tribe of Britannia, mentioned by Julius Caesar.
Trinovantibus defensis atque ab omni militum iniuria prohibitis, Cenimagni, Segontiaci, Ancalites, Bibroci, Cassi legationibus missis sese Caesari dedunt.The Trinobantes being protected and secured from any violence of the soldiers, the Cenimagni, the Segontiaci, the Ancalites, the Bibroci, and the Cassi, sending embassies, surrendered themselves to Caesar.c. 52 BCE, Julius Caesar, Commentarii de bello Gallico 5.21

Cenīmagni, ōrum, m.,

I. a British tribe in Norfolk, Suffolk, and Cambridge, Caes. B. G. 5, 21.