I. noun
( -es )
Etymology: fit (III) + -ness
1. : the quality or state of being fit or fitted
the physical fitness … of large numbers of people had been impaired by poverty — F.A.Ogg & P.O.Ray
2. : the condition of being qualified or suitable : eligibility , soundness , capacity
subjected to endurance tests to prove their fitness … for the status of manhood — Francis Birtles
the law prescribed that the ordaining bishop should assure himself … of the candidate's fitness in education and morals — G.G.Coulton
officials … should be chosen for their fitness to understand intellectual questions — Zechariah Chafee
3. : essential rightness or reasonableness : propriety , correctness , appropriateness
one observes a nice historical fitness in the fact — H.O.Taylor
no one with a sense of fitness ever docked the tail of a Shetland pony — Ben Riker
— often used in the phrase fitness of things
the sheep … lay quiet enough, having an inborn sense of the fitness of things — John Galsworthy
it does appear to be … inherent in the eternal fitness of things — T.L.Peacock
II. noun
: 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