: presumably too-TAH-tez
Gaulish: God of the Tribe
Also, Mars Toutates Cocidius (inscription, Carlisle, England)
Apollo Toutiorix (inscription, Wiesbaden, Germany)
Teutates is mentioned by Julius Caesar in The Gallic Wars; Teutates is one of a trinity mentioned by Lucan, who names him in the same breath with "horrible Esus and Taranis." According to Lucan, Teutates' victims were drowned in a cauldron (a scene of which can be seen on the Gundestrup Cauldron), while Esus' victims were flayed while hung from a tree, and Taranis' were sealed up in a hollow tree (not unlike what happened to Merlin, though).
Lucan's commentator (a medieval monk) identifies Teutates with Mercury, Esus with Mars, and Taranis with Dispater (Pluto). I differ with this. Caesar lists four gods as most important to the Gauls: first Mercury (who is likely Lugus, the Irish Lugh), then Apollo (likely Maponos, or possibly Esus or Belenos), Jupiter (Taranis--"Thunder"), Mars (Teutates), and Minerva (likely Brigantia, who is Brigid). OF course, it's difficult (and frankly foolish) to identify completely the gods of one culture with that of another; even the Romans and Greeks have some discrepancies.
As said, the name derives from teut, which means "tribe of people," equivalent to the Irish tuath, German Deutsch, and Latin Teutons. Teutates, if Mars and thus both war god and fertility god, may simply be a title for another god, which would here be the equivalent of the Irish Nuada, the Welsh Nudd, and British Nodens.