optimum

Etymology

It is borrowed from Latin optimum (“the best, that which is best”), the neuter singular of optimus (“best”) used as a noun,^{[2][3][4][5][6]} which served as the superlative of bonus (“good”).^[3][7] The origin of optimus is uncertain.^[3][2] The OED and Barnhart take its first element as perhaps related to ops (“power, resources, aid”), the source of opulent, with an extended superlative suffix,^[2][5] and Watkins, as Etymonline reports, traces it to Proto-Indo-European *op- (“to work, produce in abundance”), the sense passing from "richest" to "most esteemed".^[3] Etymonline also reports de Vaan's view that it comes from ob (“in front of”) with the superlative suffix *-tumos,^[3] and Ayto likewise suggests the preposition ob.^[8] The same Latin word, used by Leibniz for the greatest good, gave French optimisme and so optimism.^[3][8] optimum is recorded once in 1771 and otherwise only from 1913.^[2]

Earliest recorded meaning

The most favourable condition or amount: 1848, in the Commercial Review of the South and West.^[2][9] Barnhart and Etymonline date the noun to 1879,^[5][3] and Etymonline and the Shorter Oxford say it was first used in biology, of the conditions most favourable to growth or other vital processes.^[3][6]

Semantic evolution

From the biological use the word spread to any level or condition regarded as the best.^[6] The adjective, best or most favourable, especially under given conditions, is recorded from 1885 in the OED and Etymonline,^[2][3] and 1886 in Barnhart,^[5] who dates optimal, formed from the noun, to 1890.^[5] Merriam-Webster also records a climatological sense, a period warmer and drier than the present.^[9]

Timeline

• 1848 – noun, the most favourable condition, value or amount.^[2][9]
• 1879 – noun, in biology (Barnhart and Etymonline's first date).^[5][3]
• 1885 – adjective, best, most favourable.^[2][3]

Meanings

Noun

1. The amount, degree or condition that gives the best result: Sales reached their optimum in the spring.^[10][9][2]
2. In biology, the conditions of temperature, light, moisture and food most favourable to the growth and reproduction of an organism.^[9][6]
3. A period of warmer and drier climate than the present.^[9]

Adjective

1. Most favourable or advantageous; best, especially under given conditions: the optimum speed for the engine.^[10][9][2]
2. Greatest or best possible within a stated or implied limit.^[9]

Related words

• optimal
• optimize
• optimism
• optimist
• optimistic

Usage notes

The plural is optima or optimums.^[10][9][6]

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 e f g h i j k Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
5. ^ a b c d e f Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
6. ^ a b c d e Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
7. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
8. ^ a b Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
9. ^ a b c d e f g h i Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
10. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins