aqueous

Etymology

Most dictionaries take it as borrowed from Medieval Latin aqueus (“watery”),^{[2][3][4][5][6][7]} from Latin aqua (“water”),^[2][3][4] with the English suffix -ous.^[3][6] Barnhart thinks the Medieval Latin adjective was probably formed after terreus (“earthy”), from terra (“earth”).^[3] The OED instead treats the word as formed in English as if from a Latin form *aqueus with the same suffix,^[8] and Hoad and Klein as formed from aqua perhaps on the model of French aqueux (“watery”),^[9][10] which itself comes from Latin aquōsus (“abounding in water”).^[8][10][11] Etymonline traces aqua to Proto-Indo-European *akwa- (“water”).^[11]

Earliest recorded meaning

Used in the phrase aqueous humour, the watery fluid of the eye: 1643, in Charles Herle's Answer to Fernes Reply.^[8][3] Barnhart also gives 1643 for this use,^[3] while Merriam-Webster's earliest date, 1646, is for the general sense "watery".^[6]

Semantic evolution

The general sense, of the nature of water or diluted with water, appears in 1646 in Sir Thomas Browne's Pseudodoxia Epidemica.^[8][6] Johnson (1755) gave the word simply as "watery".^[12] From 1731 it was used more loosely for anything connected with water.^[8] From 1802, in John Playfair's work on the Huttonian theory, geologists used it of rocks and deposits produced by the action of water.^[8][7] In chemistry an aqueous solution is one in which water is the solvent.^[5][6] From 1879 aqueous was also used alone as a noun for the aqueous humour.^[8][6]

Timeline

• 1643 – aqueous humour, the fluid of the eye.^[8][3]
• 1646 – of the nature of water; watery.^[8][6] Etymonline dates the word to the 1640s.^[11]
• 1731 – connected with or relating to water.^[8]
• 1802 – in geology, produced by the action of water.^[8]
• 1879 – noun, short for aqueous humour.^[8]

Meanings

Adjective

1. Of, like or containing water; watery.^[7][6][8]
2. Made with or dissolved in water: an aqueous solution of salt.^[7][6]
3. (geology) Of rocks or deposits: formed from material laid down in water.^[7][6][8]
4. Of or relating to the aqueous humour of the eye.^[6]

Noun

1. (anatomy) The aqueous humour.^[6][8]

Word family

• aqueously
• aqueousness
• nonaqueous
• subaqueous
• superaqueous

Related words

• terraqueous
• aqua
• aquatic
• aquarium
• aqueduct

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
3. ^ a b c d e f g Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
4. ^ a b Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
5. ^ a b 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 f g h i j k l Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ a b c d e Collins English Dictionary (2023), Glasgow: HarperCollins
8. ^ a b c d e f g h i j k l m n o Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
9. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
10. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
11. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
12. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.