n (uncountable) The natural medium emanating from the sun and other very hot sources (now recognised as electromagnetic radiation with a wavelength of 400-750 nm), within which vision is possible.
n A source of illumination.
n Spiritual or mental illumination; enlightenment, useful information.
n (context|in the plural|now|_|rare) Facts. pieces of information; ideas, concepts.
n A notable person within a specific field or discipline.
n A point of view, or aspect from which a concept, person or thing is regarded.