Definition - What does Database Engine mean?
A database engine is the underlying system that a database uses to function. Many different technologies rely on internal "engines," which are the fundamental building blocks on which they operate.
Techopedia explains Database Engine
In general, referring to an "engine" for a technology implies that that specific module contains the core code for that technology’s operations. In database design, a database engine is composed of the component of the system that actually stores and retrieves data.
In order to streamline the use of a database engine from beyond that technology’s interface, a technology called application programming interfaces (API) has emerged. Many database tools can be accessed through these resources, rather than going through the actual database user interface.
While the database engine is often referred to as the inherent data storage system, the use of the term "engine" in IT often points toward proprietary design and ownership. A software engine is something that a company guards from the competition and preserves as a unique offering to markets. The reuse or simulation of a software engine is a controversial kind of activity that would have to be worked out between competing technology companies.