It is his battle cry. Stan Lee says that he just liked the sound of it. It is not proper Latin (Namor is "Roman" backwards) but he is basically saying something like "Despotic King!" It is unclear if this is an insult against his enemies or simply a case of him announcing his own presense as the King of Atlantis.
Sub-Mariner, also known as Namor, uses the phrase "Imperius Rex" as a declaration of his royal status and authority as the ruler of Atlantis. The phrase, which translates to "Imperious King," emphasizes his power and sovereignty over his underwater kingdom. It often serves as a rallying cry for his allies and a warning to his enemies, reinforcing his identity as a formidable leader in the Marvel Universe.
Attuma and General Krang are his biggest foes I would say, in that order.
el conejo rex
T-rex! If you ask a 5 year old he will say T-rex. If you ask an 80 year old they will say tiger or T-rex.
The correct way to say it is T-Rex and Tyrannosaurus and yes T-Rex is short for Tyrannosaurus.
I am the king
a rex was dumb that a spinosaurus could kill it is all i can say.
You say 'Tuus rex est.'
Rex Iudaeorum
rex regum
the same way in English
Rex mei mundi.