tomography

Etymology

It is formed from English tomo- + -graphy,^[2][3] the first element representing Ancient Greek τόμος (tómos, “slice, section”).^{[4][5][6][7][8]} Merriam-Webster Unabridged treats it as an international scientific word, probably first formed in German.^[2][3] Collins instead gives τομή (tomḗ, “a cutting”) as the first element.^[9] The Greek noun is an o-grade form of the base of τέμνω (témnō, “to cut”),^[4] from Proto-Indo-European *tem- (“to cut”), and is also the source of tome.^[8][4]

Earliest recorded meaning

An X-ray technique for imaging a single plane of the body: 1935, in the British Journal of Radiology: "The most significant field of application for the method of reproducing body layers (tomography) will, in practice, be lung diagnosis."^[4] Merriam-Webster Unabridged and Etymonline give the same year.^[2][8]

Semantic evolution

At first the word named a process in which an X-ray source and detector pivot about the object so that everything outside one plane is blurred, now also called focal plane tomography.^[4] It was later widened to any process that builds a cross-sectional image from the passage of electromagnetic waves, electrons or the like through one plane at different angles, and to the combining of such images into a three-dimensional picture.^[4] The Shorter Oxford notes that the techniques use X-rays or ultrasound and are now often processed by computer.^[7] The related tomograph (1935) was probably modelled on German for the apparatus, and tomogram (1936) for the image.^[4] By 1974 the journal Radiology wrote of computerized axial tomography, or CT scanning.^[4]

Timeline

• 1935 – imaging of a single plane section of the body by X-rays.^[4][2][8]
• 1974 – computerized axial tomography, abbreviated CT.^[4]

Meanings

Noun

1. A technique of radiography in which one plane of the body appears sharp while the planes on either side are blurred.^[2][4]
2. Any of various techniques that produce images of successive cross sections of the body or another solid object, using X-rays, ultrasound and the like, often combined by computer into a three-dimensional image.^[7][9][4]

Word family

• tomogram
• tomographic
• computed tomography
• positron emission tomography

Related words

• tome
• tomograph
• -tomy

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
3. ^ a b Gove, Philip Babcock, ed. (1961), Webster's Third New International Dictionary of the English Language, Unabridged, Springfield, Mass.: G. & C. Merriam
4. ^ a b c d e f g h i j k l Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
5. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
6. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
7. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
8. ^ a b c d Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
9. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins