fitness

Etymology

It is formed from English fit + -ness.^{[2][3][4][5][6]} The adjective fit, recorded from about 1440, is of unknown origin;^[2][3] Etymonline suggests it may come from a Middle English noun fit (“an adversary of equal power”),^[3] and the OED thinks its meaning was partly influenced by feat.^[2]

Earliest recorded meaning

The quality of being suitable, qualified or competent: 1574, in Baret's Alvearie.^[2] Merriam-Webster dates the word to 1580,^[5][7] and Etymonline to the 1570s.^[3]

Semantic evolution

Until the 20th century the word meant suitability and propriety rather than health.^[3][2] From 1597, in Hooker, it was the quality of being fit and proper for the circumstances; from 1648 it meant moral worthiness;^[2] the phrase the eternal fitness of things became current in the 18th century after Clarke's ethical theory of 1706.^[2] Shakespeare used it once in Hamlet (1604) for readiness or inclination; from 1658 to 1793 it could mean the exact fit of something in size and shape.^[2] Johnson (1755) defined it as "propriety; meetness; justness; reasonableness".^[8] Spencer gave it a biological sense in 1865, the capacity of an organism to survive and reproduce in its environment,^[2] and geneticists made it a numerical measure from 1953.^[2] The sense of physical health and strength dates from 1935,^[3] and the American Heritage Dictionary lists it first.^[9] In British Black slang of the late 1990s fitness was sexual attractiveness, or an attractive young woman, from the slang sense of fit.^[10]

Timeline

• 1574 – the quality of being suitable, qualified or competent.^[2]
• 1597 – propriety; being fit for the circumstances.^[2]
• 1604 – readiness, inclination, in Shakespeare's Hamlet.^[2]
• 1648 – moral worthiness.^[2]
• 1658 – exact correspondence of size and shape (obsolete by 1793).^[2]
• 1706 – the (eternal) fitness of things, in Clarke.^[2]
• 1865 – biology, the capacity to survive and reproduce, in Spencer.^[2]
• 1935 – the state of being physically fit.^[3]
• 1953 – genetics, a numerical measure of reproductive success.^[2]
• 1997 – British Black slang, attractiveness.^[10]

Meanings

Noun

1. Good physical condition, especially from exercise and a sound diet: She started cycling to work to improve her fitness.^[9][5][2]
2. The quality of being suitable or qualified for something: his fitness for the post.^[5][7][2][4]
3. Propriety; suitability to the circumstances: the fitness of things.^[2][4][8]
4. (biology) The capacity of an organism to survive and pass on its genotype to offspring, compared with competing organisms.^[7][2][4]
5. (British slang) Sexual attractiveness; also, an attractive young woman.^[10]

Word family

• inclusive fitness

Related words

• fit
• fitting

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o p q r s t u v Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d 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. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
7. ^ a b c Merriam-Webster's Collegiate Dictionary (2003), 11th ed., Springfield, Mass.: Merriam-Webster
8. ^ a b Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
9. ^ a b The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin
10. ^ a b c Green, Jonathon (2010), Green's Dictionary of Slang, London: Chambers; digital ed. 2016–, https://greensdictofslang.com