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fitness

American  
[fit-nis] / ˈfɪt nɪs /

noun

  • fitness
    plural
  1. health.

  2. capability of the body of distributing inhaled oxygen to muscle tissue during increased physical effort.

  3. Also called Darwinian fitnessBiology.

    1. the genetic contribution of an individual to the next generation's gene pool relative to the average for the population, usually measured by the number of offspring or close kin that survive to reproductive age.

    2. the ability of a population to maintain or increase its numbers in succeeding generations.


fitness British  
/ ˈfɪtnɪs /

noun

  1. the state of being fit

  2. biology

    1. the degree of adaptation of an organism to its environment, determined by its genetic constitution

    2. the ability of an organism to produce viable offspring capable of surviving to the next generation

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Noun Inflected Forms

Etymology

Origin of fitness

First recorded in 1570–80; fit 1 + -ness

Explanation

Fitness is good physical condition. If you're a fitness nut and you're constantly working out, everybody else at the gym might be eyeing your sculpted muscles with envy and marveling at your stamina and strength. Fitness can also refer to your being fit, or qualified, for something. If you show up in ragged jeans and a dirty t-shirt to interview for a job in the clean room of a microchip factory, your interviewer might question your fitness for the position. For a ship, fitness is a measure of whether it's seaworthy. In biology, an organism's fitness for a particular environment is its ability to survive and reproduce in those conditions.

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Vocabulary lists containing fitness

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

The Athleta segment offers fitness apparel for women.

From MarketWatch Aug. 28, 2026

Another part of why Saka looks like he is in a flow state so early in the season is the return of Kai Havertz, Martin Odegaard and Ben White to full fitness.

From BBC Aug. 27, 2026

Joao Pedro spent the rest of his summer in Rio training with Goncalves, his personal fitness coach since childhood, surrounded by friends and following many of the same routines he always has.

From BBC Aug. 26, 2026

Unlike much of the biking and climbing, these extreme outdoor adventures don’t require experience or superb fitness, just the nerve to take the leap—literally.

From The Wall Street Journal Aug. 24, 2026

It is done by simply passing the bits around from mind to mind, until something like natural selection makes the final selection, all on grounds of fitness.

From "The Lives of a Cell" by Lewis Thomas

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