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

Each resort offers all-suite accommodations and its own freshwater pool, fitness center, beach and pool loungers, and complimentary water sports including kayaks and standup paddleboards. —Allison Tibaldi, USA Today, 24 Jan. 2026

Denise Austin is celebrating nearly four decades in fitness and proving consistency pays off. —Stephanie Giang-Paunon, FOXNews.com, 24 Jan. 2026

These corridors allow guests to move between rooms, dining spaces, the spa, and fitness facilities without going outdoors—especially useful in winter—and double as informal galleries lined with work by regional artists. —Condé Nast, Condé Nast Traveler, 24 Jan. 2026

Hardware sales have been decreasing, which is problematic since subscriptions for connected fitness—arguably the most sustainable segment—rely significantly on consumers owning Peloton equipment. —Trefis Team, Forbes.com, 23 Jan. 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