The snake is a long, legless reptile that moves by flexing its muscular body in smooth, flowing curves. Snakes live on every continent except Antarctica, in habitats ranging from deserts to rainforests to oceans. Some species are venomous and use their fangs to inject venom into prey, while others constrict their victims by wrapping around them and squeezing. All snakes are carnivores, swallowing their food whole because they can't chew.

A snake's forked tongue constantly flicks in and out, collecting scent particles from the air to help it navigate and hunt. When a snake grows too large for its skin, it sheds the old skin in one piece, revealing fresh scales underneath. Some snakes, like the tiny threadsnake (barely longer than a pencil), are harmless, while others, like the king cobra, command respect and caution.

People also use snake to describe someone who acts friendly but is secretly disloyal or treacherous. If a classmate pretends to be your friend but spreads rumors behind your back, someone might call them a snake. When you snake through a crowd, you weave your way through narrow spaces, moving like the reptile itself.