fang
A long, sharp tooth used by animals to bite or catch prey.
A fang is a long, pointed tooth that certain animals use to catch prey or deliver venom. Snakes have hollow fangs that work like tiny needles, injecting venom when they bite. Spiders use their fangs to pierce prey and release digestive fluids. Wolves, lions, and other predators have sharp fangs for gripping and tearing meat.
Not every sharp tooth is a fang. Your canine teeth are pointy, but they're much smaller and less specialized than true fangs. A fang is typically longer than other teeth and often curves slightly, making it more effective for its purpose. When a rattlesnake strikes, it can fold its fangs back against the roof of its mouth when not in use, then swing them forward in an instant.
Vampire bats really do have fangs, which they use to make small cuts in sleeping animals before lapping up blood. In fiction, vampires have exaggerated fangs that supposedly pierce victims' necks, though real vampire bats are actually quite small and prefer livestock to people.