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

• 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

Think of it as cognitive fitness—something that requires ongoing attention and effort. —Cornelia C. Walther, Forbes.com, 12 Sep. 2025

Meiler’s fierce competitive spirit, even at the age of 91, is proof that fitness doesn’t have a shelf life. —Cindy Kuzma, SELF, 11 Sep. 2025

For something more personal, the Fitbit Sense fitness tracker is down 34% to $153, giving you stress tracking, sleep insights, and health tools that actually help day to day. —Shubham Yewale, PC Magazine, 11 Sep. 2025

Preseason fitness with Dallas surprised her. —Tamerra Griffin, New York Times, 10 Sep. 2025

Word History

First Known Use

1580, 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