Sabertooth refers to the physical trait of having teeth similar to a saber-toothed cat, i.e., canine teeth which extend outside the mouth and typically past the jawline.
It does not refer to saber-toothed cats specifically. The tag for that is smilodon. Note that the tags are not mutually exclusive; a picture tagged smilodon is quite likely to require the sabertooth tag as well.
The following tags are aliased to this tag: sabretooth