a polyhedron with two congruent and parallel faces (the bases) and whose lateral faces are parallelograms
"The teacher explained that a triangular prism is a polyhedron with two congruent, parallel triangular bases connected by three rectangular lateral faces."
optical device having a triangular shape and made of glass or quartz; used to deviate a beam or invert an image
"The scientist placed the triangular glass prism in the path of sunlight to separate it into its component colors."
A polyhedron with parallel ends of the same size and shape, the other faces being parallelogram-shaped sides.
"The transparent glass prism refracted the light into a spectrum of colors as it passed through its geometric form."
In plain English: A prism is a clear block of glass that bends light to split it into different colors.
"The prism split the sunlight into a rainbow of colors on the floor."
Usage: In optical contexts, a prism refers to a transparent object that refracts light into its constituent colors, distinct from the geometric solid defined by its polygonal faces. Avoid confusing this term with "prism" as a verb meaning to separate or divide something into parts.
The word prism entered English from Late Latin and Ancient Greek, where it originally referred to anything that was sawn. Its root comes from a verb meaning "to saw," though the ultimate origin of this verb remains unknown.