T. Rex Definition
tē rĕks
noun
A very large carnivorous tyrannosaurid dinosaur (Tyrannosaurus rex) of the Cretaceous Period, having a large head and teeth and short forelimbs with two claws.
American Heritage
Tyrannosaurus rex.
Webster's New World
abbreviation
(informal) Alternative form of T. rex. Abbreviation of Tyrannosaurus rex.
Wiktionary
pronoun
Origin of T. Rex
Abbreviation of Tyrannosaurus Rex, the group's former name, cf. T. rex being the abbreviated form of Tyrannosaurus rex, the animal for which the group were named after.
From Wiktionary