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

Hyrox is an indoor fitness race or competition that combines running with functional exercises. —Mary Walrath-Holdridge, USA Today, 11 Apr. 2026

But by day, Blaze flips back to Kristin Lubeskie, a 25-year-old Fort Lauderdale personal fitness coach who never watched wrestling until two years ago. —Phillip Valys, Sun Sentinel, 11 Apr. 2026

And for King, that consistency factor goes building physical strength or mental fitness, a weightlifting plan or a breathing practice. —Maggie Ryan, Flow Space, 10 Apr. 2026

And for both Swalwell and Katie Porter, there are legitimate questions regarding their fitness for office. —Douglas Schoen, Oc Register, 10 Apr. 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