n.1. a. A section formed by a plane cutting through an object, usually at right angles to an axis.
b. A piece so cut or a graphic representation of such a piece.
2. Physics A quantity, measured in units of barns, used to express the probability of an encounter between particles over a given area in a collision. Also called collision cross section.
3. Statistics A sample meant to be representative of a whole population.
4. Informal A variety; a diversity.