Prism

How to spell prism

5 letters · 2 syllables

How to pronounce prism

Say the part in capitals loudest.

What does prism mean?

1. nounA transparent solid, often triangular, that refracts light into a spectrum, or any solid geometric shape with flat parallel ends and rectangular sides.

Prism in a sentence

• The glass prism on the windowsill scattered sunlight into rainbow colours across the wall.

• In the physics lab she used a prism to separate white light into its component wavelengths.

Where does prism come from?

Language of origin: Greek

This word comes from the Greek prisma, meaning literally 'something sawn off' or 'a sawn piece', which was formed from the verb prizein, 'to saw'. The image is of a solid block cut cleanly with straight edges, since a classic prism is bounded by flat polygonal faces. The term passed into Late Latin as prisma and entered English in the late 1500s, first as a geometric term for such a solid. Once scientists like Isaac Newton used triangular glass prisms to split white light into a spectrum of colours, the word became firmly tied to optics. The spelling preserves the Greek ending, which is why it closes with the unusual consonant cluster -sm rather than a softer sound.

How the word is built

• prism (from Greek prisma: something sawn, a sawn-off piece)