The Concise Oxford Dictionary of World Religions (1705 page)

1. In canonical Buddhism, the outward aspect or general appearance of an object; that aspect which we find attractive (
abhijjh
) or repulsive (
domanassa
) when our senses perceive things.
2. In meditation, the perceptual objects used for contemplation (
kamma
h
na
) are referred to as nimitta because they function as a mark, sign, or image on which the eye and mind focus their attention.
3. According to the P
li Commentaries (
A
hakath
), at the last moment of consciousness before death the sign of previous
karma
(
kamma-nimitta
) together with the sign of future destiny (
gati-nimitta
) arise as mental objects, as an indication of that person's impending rebirth.
4. It is the term for the ‘signs’ or ‘omens’ of old age, sickness, death, and the wandering mendicant which, according to legend, convinced the Buddha to leave home and lead the ascetic life.
5. In the Yogac
rya (
Vijñ
nav
da
) branch of Buddhism, it is the term for the perceived object, which has no existence independently of the perceiver but is merely a representation of his inner consciousness