a section made by a plane cutting anything transversely, esp. at right angles to the longest axis.

a piece so cut off.

a photograph, diagram, or other pictorial representation of such a section.

the act of cutting anything across.

a typical selection; a sample showing all characteristic parts, relationships, etc.

a cross section of American opinion.

Surveying . a vertical section of the ground surface taken at right angles to a survey line.

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.