- a realization or actuality as opposed to a potentiality.
- (in vitalist philosophy) a vital agent or force directing growth and life.
- (in the philosophy of Aristotle) actuality as opposed to potentiality
- (in the system of Leibnitz) the soul or principle of perfection of an object or person; a monad or basic constituent
- something that contains or realizes a final cause, esp the vital force thought to direct the life of an organism
