fitness

noun

fit·​ness ˈfit-nəs 

1

: the quality or state of being fit

2

: the capacity of an organism to survive and transmit its genotype to reproductive offspring as compared to competing organisms

also : the contribution of an allele or genotype to the gene pool of subsequent generations as compared to that of other alleles or genotypes

Synonyms of fitness

• health
• wellness
• strength

Examples of fitness in a Sentence

a gymnastics program promoting fitness and agility in school-aged children

I have to question the fitness of wearing a bright red dress to a funeral.

Recent Examples on the Web

During long periods of inactivity, blood flow still slows, large muscles remain underused, and metabolic processes become less efficient, regardless of your fitness level. — Jakob Roze, Health, 23 July 2026

One North Carolina church built a fitness center that's free to use. — Joe Hernandez, NPR, 23 July 2026

Reyes also noted that the Pentagon's concerns about the costs of hormone therapy and concerns about fitness would apply to cisgender soldiers as well, though it was only used as a basis to target transgender soldiers. — Peter Charalambous, ABC News, 23 July 2026

The hypervirulent subpopulation had a fitness disadvantage in the urinary tract—the origin of the infection. — Beth Mole, ArsTechnica, 23 July 2026

Word History

First Known Use

1574, in the meaning defined at sense 1

Phrases Containing fitness

• physical fitness

Rhymes for fitness

• witness
• eyewitness
• unfitness

Medical Definition

fitness

noun

fit·​ness ˈfit-nəs 

: the capacity of an organism to survive and transmit its genotype to reproductively fertile offspring as compared to competing organisms

also : the contribution of an allele or genotype to the gene pool of subsequent generations as compared to that of other alleles or genotypes