Smilodon was a large animal, roughly the size of a lion, but built like a bear (1). The largest Smilodon species is Smilodon populator, weighing between 882 lb to 900 lb (1)(3).
Smilodon had large sabers (1)(2)(3) in the front of its mouth.
Smilodon populator: 882-900 lb (1)(3)
Smilodon gracilis:121-221 lb (3)
Smilodon fatalis: 353-617 lb (3)
Teeth: The canine teeth of Smilodon are long, blade-like and are curved slightly towars the throat (1)(3). Canines are the saber teeth that are the main charateristic of Smilodon (1)(2)(3).
Jaw: The jaw of Smilodon can open up to 130 degree angle (3). On the contrary, modern cats can only extend their jaws to a 60 degree angle (3)(4).