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.
Inborn; existing or having existed since birth.
Instinctive; coming from instinct.
Joined by the base to the very tip of a filament.
Originating in, or derived from, the constitution of the intellect, as opposed to acquired from experience.