filtration

Etymology

It is borrowed from French filtration (“the action of filtering”), recorded in Middle French from 1578, and its probable source borrowed from New Latin filtrātiō, recorded from 1532.^[2] Etymonline also suggests the French word, with a question mark.^[3] The Latin noun is formed from the past participle stem of Medieval Latin filtrō (“to filter”),^[2] itself from filtrum (“felt”), felt having been used to strain liquids.^[3] Etymonline traces filtrum to Proto-West Germanic *filtiz, while Wiktionary derives it from Frankish *filtir, from Proto-West Germanic *felt, the source of felt.^[3][1] The Shorter Oxford takes it as French, from filtrer (“to filter”).^[4]

Earliest recorded meaning

The action or process of filtering something: 1602, in William Clowes's treatise on the cure of struma.^[2] Etymonline dates the word to about 1600,^[3] and Merriam-Webster to 1605.^[5]

Semantic evolution

The word was first used of straining a liquid through a filter to clear it, and soon also in extended and figurative senses.^[2] Johnson (1755) described it as a method of making liquors fine and clear, citing straining through paper whose small pores let only the finer parts pass.^[6] From 1644, in Kenelm Digby, it also meant the passing of a liquid through a filter or its seeping through a porous substance;^[2][4] the OED notes that French did not have this sense of percolation until 1690.^[2] Merriam-Webster also gives the sense "diffusion".^[5]

Timeline

• 1602 – the action or process of filtering.^[2]
• 1644 – the passing of a liquid through a filter; percolation.^[2]

Meanings

Noun

1. The act or process of filtering something: the filtration of drinking water.^[7][8][5][2]
2. The passing of a liquid or gas through a filter or a porous substance; percolation, also diffusion.^[5][2][4]

Word family

• ultrafiltration

Related words

• infiltration
• filter
• filtrate
• infiltrate
• felt

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
6. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
7. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
8. ^ Collins English Dictionary (2023), Glasgow: HarperCollins