fitness

American  

[fit-nis] / ˈfɪt nɪs /

noun

1. health.

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

3. Also called Darwinian fitness.  Biology.

   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.

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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

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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.

Example Sentences

Earlier this month, Trump invited a group of children to the Oval Office to celebrate the return of the Presidential Fitness Test.

From Salon • May 26, 2026

And there’s a case for serious athletes, who could use the Fitness setting to actually add resistance during workouts.

From The Wall Street Journal • May 21, 2026

The question, asked by YouGov, was sparked by a Tuesday event in the Oval Office, when the president revived the Presidential Physical Fitness Award.

From Salon • May 11, 2026

In reality, the new-member numbers were below last year’s but still net positive, and Planet Fitness is significantly larger than competitors and grows faster than they do, he said.

From MarketWatch • May 8, 2026

We were supposed to compare ourselves to the President’s Council on Physical Fitness goals that all American boys should be trying to reach so we wouldn’t die of heart attacks someday.

From "Okay for Now" by Gary D. Schmidt

Related Words

• adequacy
• compatibility
• competence
• consistency
• eligibility
• preparedness
• qualification
• readiness
• suitability