cumulus

Etymology

It is borrowed from Latin cumulus (“a heap, pile, mass”);^[2][3][4][5] Merriam-Webster takes the cloud sense as New Latin.^[5] Etymonline derives the Latin word from Proto-Indo-European *ku-m-olo-, a suffixed form of Proto-Indo-European *keue- (“to swell”),^[4] and Klein, who compares the formation of tumulus (“a mound”), relates it to Ancient Greek κῦμα (kûma, “a wave”) and cavus (“hollow”).^[6] From the same Latin word come cumulate and accumulate.^[4]

Earliest recorded meaning

A heap or pile; an accumulation: 1659, in Henry Hammond's Paraphrase and Annotations on the Psalms.^[2][3][5]

Semantic evolution

The OED's first sense also covers the conical top of a heaped measure, and so the crowning mass of something.^[2] The meteorological sense comes from Luke Howard's Modifications of Clouds (1803), which named the simple forms of clouds: a cumulus is made of rounded masses heaped on one another over a nearly flat base.^[2][3][4] In 1882 anatomists applied the word to the thickened part of the lining of the Graafian follicle in which the egg is embedded.^[2][7] Merriam-Webster Unabridged still records the old general sense of a heap or accumulation, quoting E. B. White.^[5]

Timeline

• 1659 – a heap, pile; an accumulation.^[2][3][5]
• 1803 – a cloud of rounded masses heaped on a flat base, in Luke Howard.^[2][3][4]
• 1882 – in anatomy, the mass of cells around the egg in a Graafian follicle.^[2]

Meanings

Noun

1. A dense, white, puffy cloud with a flat base and rounded, heaped tops, formed by rising air: Cumulus clouds piled up over the hills by midday.^[7][5][2]
2. A heap or accumulation.^[5][2][8]
3. (histology) The mass of cells around a newly released egg cell in a Graafian follicle.^[7][2]

Word family

• stratocumulus

Related words

• cumulate
• accumulate
• cumulative

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
4. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
5. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
6. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins
8. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press