Being an essential and permanent part of something.
Being an included feature that normally comes as an extra.
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.
Firmly established in one's beliefs or habits; having a specified characteristic, identity, etc. deeply ingrained in one's nature.
Having the fibres dyed before they are formed into cloth.