The effort of performing or doing something. • Something done, often so as to accomplish a purpose. • A way of motion or functioning. • Fast-paced activity. • The way in which a mechanical device acts when used; especially a firearm. • The way in which cartridges are loaded, locked, and extracted from the mechanism. • A physical mechanism of a firearm or other device. • The mechanism, that is the set of moving mechanical parts, of a keyboard instrument, like a piano, which transfers the motion of the key to the sound-making device. • The distance separating the strings and the fingerboard on a string instrument. • Sexual intercourse. • Combat. • A charge or other process in a law court (also called lawsuit and actio). • A way in which each element of some algebraic structure transforms some other structure or set, in a way which respects the structure of the first. Formally, this may be seen as a morphism from the first structure into some structure of endomorphisms of the second; for example, a group action of a group G on a set S can be seen as a group homomorphism from G into the set of bijections on S (which form a group under function composition), while a module M over a ring R can be defined as an abelian group together with a ring homomorphism from R into the ring of group endomorphisms of M (which is also called the action of R on M). • The product of energy and time, especially the product of the Lagrangian and time. • The event or connected series of events, either real or imaginary, forming the subject of a play, poem, or other composition; the unfolding of the drama of events. • The attitude or position of the several parts of the body as expressive of the sentiment or passion depicted. • spin put on the bowling ball. • A share in the capital stock of a joint-stock company, or in the public funds. • A religious performance or solemn function, i.e. action sermon, a sacramental sermon in the Scots Presbyterian Church. • A process existing in or produced by nature (rather than by the intent of human beings). • Purposeful behavior. • A demonstration by activists. • The opportunity to act during a betting round. • Heavy betting activity.