prism

Etymology

It is borrowed from Late Latin prisma (“a prism”),^[2][3][4][5] recorded in Latin as a geometrical term from the 5th century,^[2] from Ancient Greek πρῖσμα (prîsma, “something sawn; sawdust”), used in Hellenistic Greek, by Euclid, for the geometrical prism.^[2][6] The Greek noun comes from πρίζω (prízō, “to saw”), a rarer form of πρίω (príō),^[2][1][4] with the suffix -μα (-ma).^[2][1] The verb is of uncertain origin;^[6][1] Barnhart, Klein and Partridge compare Albanian prish (“to break up, spoil”),^[3][7][8] and Barnhart traces both to Proto-Indo-European *pris- (“to crush”).^[3] Etymonline suggests that Euclid chose the word with the image of a column whose sides had been sawn off,^[6] and Ayto sees the shape of a sawn-off piece behind it.^[9] The Greek noun is related to prion.^[2][7] French prisme is recorded in geometry from 1609 and in optics from 1637, and Italian prisma in Galileo.^[2]

Earliest recorded meaning

In geometry, a solid figure whose two ends are equal, similar and parallel rectilinear figures and whose sides are parallelograms: 1570, in H. Billingsley's English Euclid.^[2][3][6]

Semantic evolution

The word came into English as a term of geometry, and the optical sense, a transparent body of this shape that refracts light, followed in 1612.^[2][3][6] Ayto places the optical use at the beginning of the 17th century,^[9] and Johnson (1755) defined it only as a glass prism, quoting Newton's Opticks.^[10] The spectrum made by refraction through a prism was itself called a prism from 1669, a use now rare.^[2] Figurative uses date from 1791.^[2] Any object of prismatic shape could be called a prism from 1660; civil engineers applied the word to a cutting or embankment measured as a prism from 1851, and crystallographers to a form of three or more faces parallel to the vertical axis from 1878.^[2] The Greek sense "sawdust" was briefly borrowed as well (1656–99), in Blount's Glossographia.^[2] The adjective prismatic (1709, in Pope) is a shortening of prismatical (1654), influenced by French prismatique.^[3]

Timeline

• 1570 – geometry, a solid figure with parallel equal ends and parallelogram sides.^[2][3][11]
• 1612 – optics, a transparent body that refracts light.^[2][3]
• 1656 – sawdust (obsolete by 1699).^[2]
• 1660 – any object shaped like a prism.^[2]
• 1669 – the spectrum produced by a prism.^[2]
• 1791 – figurative use.^[2]
• 1851 – civil engineering, a cutting or embankment measured as a prism.^[2]
• 1878 – crystallography, a form whose faces are parallel to the vertical axis.^[2]

Meanings

Noun

1. A transparent block, usually of glass with triangular ends, that refracts or reflects light and splits white light into a spectrum, used in binoculars, periscopes and spectroscopes.^[12][11][2]
2. (geometry) A polyhedron with two parallel, equal polygonal ends and sides that are parallelograms.^[12][11][2]
3. (crystallography) A crystal form made of faces parallel to the vertical axis.^[12][2]
4. Anything shaped like a geometrical prism.^[11][2]

Word family

• prismatic
• prismatoid
• prismoid

Related words

• prion

References

1. ^ a b c d e Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
4. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
5. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
6. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
7. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
8. ^ Partridge, Eric (1966), Origins: A Short Etymological Dictionary of Modern English, 4th ed., London: Routledge & Kegan Paul
9. ^ a b Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
10. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
11. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
12. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins