What is terrarium?

A self-contained environment, usually with only plants inside, that was originally called a Wardian Case. They can be made out of fish tanks with flouroscent hoods, clear empty wine bottles or demijohns, or something as simple as a fish bowl. If there are frogs or herps and/or an exposed pool of water inside, it is considered to be a vivarium, but you can still call it a terrarium.