A person with extensive knowledge or ability in a given subject.
A player ranking just below master.
Extraordinarily capable or knowledgeable.
Characteristic of an expert.
A person, principle, or thing which acts as a guide; a guiding light; also, something which attracts much attention; a centre of attention.
The star visible to the naked eye which was in the past, is now, or will be in the future nearest a celestial pole of a planet.