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

Training, fitness and protective equipment allow firefighters to work in these extraordinary environments. — Julian L. Gallegos, The Conversation, 27 Aug. 2026

Henry, who suffered an ACL in his right knee in September 2017, and Hickey have struggled for form and fitness since then. — Jay Harris, New York Times, 26 Aug. 2026

Rage cycling sessions, anxiety yoga and dozens of similar fitness initiatives have gained traction in recent years, inviting people to choose workout classes based on experiences and emotions. — Sneha Dhandapani, CNN Money, 25 Aug. 2026

Just two sprints a day, totaling under 40 seconds, can improve your VO₂ max — a key measure of cardiorespiratory fitness — within two months. — Brittney Melton, NPR, 25 Aug. 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