Cross-section

[kraws-sek-shuh n, kros-] /ˈkrɔsˈsɛk ʃən, ˈkrɒs-/

adjective
1.
Also, cross-sectional. of or relating to a cross section.
verb (used with object)
2.
to make or divide into a cross section.
noun
1.
a section made by a plane cutting anything transversely, especially at right angles to the longest axis.
2.
a piece so cut off.
3.
a photograph, diagram, or other pictorial representation of such a section.
4.
the act of cutting anything across.
5.
a typical selection; a sample showing all characteristic parts, relationships, etc.:
a cross section of American opinion.
6.
Surveying. a vertical section of the ground surface taken at right angles to a survey line.
7.
Also called nuclear cross section. Physics. a quantity expressing the effective area that a given nucleus presents as a target to a bombarding particle, giving a measure of the probability that the particle will induce a reaction.
noun
1.
(maths) a plane surface formed by cutting across a solid, esp perpendicular to its longest axis
2.
a section cut off in this way
3.
the act of cutting anything in this way
4.
a random selection or sample, esp one regarded as representative: a cross section of the public
5.
(surveying) a vertical section of a line of ground at right angles to a survey line
6.
(physics) a measure of the probability that a collision process will result in a particular reaction. It is expressed by the effective area that one participant presents as a target for the other
n.

also cross section, 1748, originally in engineering sketches, from cross (adj.) + section (n.). Figurative sense of “representative sample” is from 1903.
cross section
In particle physics, an expression of the probability of the occurrence of an event, typically the scattering of subatomic particles, over a given area.