Being an included feature that normally comes as an extra.
Being an essential and permanent part of something.
Constructed as a non-detachable part of a larger structure.
Anything (such as a piece of furniture, or a software feature) that is built in, not added as an extra.
Explicitly defined, described or recognized as a reference.
Of a religion, church etc.: formally recognized by a state as being official within that area.
Having been in existence for a long time and therefore recognized and generally accepted.