Actually, a bone handles old carbon steel slip joint could be a tactical knife if called upon, but I know that's not what you meant.
If the knife looks like it should be a prop in one of those "beat 'em up, shoot 'em up, blow 'em up" movies, is black, has a blade shape that is generally useless for most general cutting tasks, is black, has emblems, names, symbols and other manner of regalia tattoed all over it, is black and has a name akin to "Blood Drainer, Combat Hero, Covert SpecWar Ninja, Rambo Tac, Tic Tac, Tac Flak, Black Tac, Tac Black, Tactical Cuticle, Tactical Testicle" or anything similar and ... is black, it could be called a tactical knife.
In other words, if I took my stag handled Marbles Campcraft (which only field dresses deer, skins deer and cuts pepperoni at the deer camp card game), spray painted it black, put some military looking symbols and names on it, I could call it "tactical." Put it into a cheap, upside down, inside out, quick draw, deep cover carry contraption and someone will likely buy it.