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

These chronic infections likely weakened soldiers, reducing fitness for duty. —Laura Baisas, Popular Science, 19 Dec. 2025

For the people that do [fitness challenge] 75 Hard, just do 365 moderate. —Ana Colón, Glamour, 18 Dec. 2025

The test, which includes calisthenics and running, was created by the Eisenhower Administration in 1956 because of Cold War anxieties about the potential military fitness of young men and women. —Dr. James S. Gordon, Time, 18 Dec. 2025

For those seeking a holistic wellness experience, ZUMA Wellness Center and Racquet Sports Facility provides state-of-the-art fitness classes, including yoga, strength, and suspension training, as well as steam rooms, a lap pool, and more. —Robb Report Studio, Robb Report, 18 Dec. 2025

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