Hey Jerico2day, I think DB is considered a language, more than an engine. Most engines have some kind of map editor that comes with it, & code that you can make work together, in multiple files, so on & so forth.
I personaly, consider DB an actual language, rather than an engine. An engine is considered by most other "engines", a tool to easily create games, with map editors, a language, model editors, etc, which DB doesnt have. Sure you can go out & get a map editor, or a model editor, but they dont come with DB.
Sure the engine is what runs everything, but you have to get external resources, which cant be considered an actual engine, unless they give out a free map editor, a way to make an easy menu, a way to make code, to no code (considered "click & create"), but there is an engine to every programing language, its just not considered an engine. But thats just my belief.