LATIN DICTIONARYLexicon Latīnum
proper noun · masculinesecond declension

Gellius

Gellius m sg (genitive Gelliī or Gellī)
Classical[ˈɡɛl.li.ʊs]Ecclesiastical[ˈd͡ʒɛl.li.us]

Meaning

  1. masculinesingulara Roman nomen gentile, gens or "family name" famously held by
  2. masculinesingularAulus Gellius, a Roman grammarian

Declension

declension
formsingularplural
nominativeGellius—
genitiveGelliī
Gellī		—
dativeGelliō—
accusativeGellium—
ablativeGelliō—
vocativeGellī—

Gellĭus, a,
I. name of a Roman gens; so the historians, Gelii, Cic. Div. 1, 26, 55; id. Leg. 1, 2, 6: L. Gellius, a friend of Cicero, id. ib. 1, 20, 53; id. Balb. 8, 19; 14, 33; and esp.: Aulus Gellius (on account of the abbreviation A. Gellius, formerly falsely called Agellius), a grammarian of the first half of the second century of the Christian era, author of the Noctes Atticae: vir elegantissimi eloquii et multae ac facundae scientiae (Gellius), Aug. Civ. Dei, 9, 4.—
II. Deriv.: Gellĭānus, i, m., a slave of one Gellius, Labeo ap. Gell. 13, 12, 4.

Quick answers

What does Gellius mean in Latin?
Gellius, a proper noun, means “a Roman nomen gentile, gens or "family name" famously held by”.
What is the genitive of Gellius?
The genitive singular is Gelliī. Gellius is masculine, second declension.
How do you pronounce Gellius?
In classical Latin, [ˈɡɛl.li.ʊs]; in ecclesiastical (church) Latin, [ˈd͡ʒɛl.li.us].