n. In metaphysics, the determination or contraction of a general nature to an individual mode of existence; the development of the individual from the general.n. Separate or individual existence or independence; that by which such individuality is developed and maintained.n. In biology: A general term summarizing the conditions for the maintenance and perpetuation of an individual organism, when these conditions are considered collectively and in contrast with those which conduce to the generation of new beings.n. A unifying principle or a cause of individuality.n. The unification of two distinct types of organisms into an individual whole, such as the lichen-thallus.