A section created by a plane cutting a solid perpendicular to its longest axis WordNet 3.0 & Open English WordNet

In geometry and science, a cross section is the non-empty intersection of a solid body in three-dimensional space with a plane, or the analog in higher-dimensional spaces. Wikipedia

The intersection of a body in 3D space with a plane, or the analog in higher-dimensional space. Cutting an object into slices creates many parallel cross sections. A cross section of 3D space that is parallel to two of the axes is a contour line Wikidata

An image that shows an object as if cut along a plane, usually at right angles to a main axis. OmegaWiki

A section formed by a plane cutting through an object, usually at right angles to an axis. Wiktionary

Section formed by a plane cutting through an object. Wiktionary (translation)