al·lo·saur·us 
(ăl′ə-sôrəs)
(ăl′ə-sôrəs)n.
A very large allosaurid dinosaur of the genus Allosaurus of the late Jurassic Period, having a pair of bony bumps above the eyes. Also called allosaur.
[New Latin, genus name : Greek allos, other (because the imperfectly preserved vertebrae of the first specimen to be described appeared to have an hourglass shape unlike those of other dinosaurs); see ALLO- + Greek sauros, lizard.]