noun a form the planes of which are parallel to the vertical axis. ·see form, ·noun, 13.
2. prism ·noun a solid whose bases or ends are any similar, equal, and parallel plane figures, and whose sides are parallelograms.
3. prism ·noun a transparent body, with usually three rectangular plane faces or sides, and two equal and parallel triangular ends or bases;
used in experiments on refraction, dispersion, ·etc.