- An inherited characteristic.
Definition from: Merriam-Webster's Medical Dictionary by Merriam-Webster Inc.
- A trait is a specific characteristic of an organism. Traits can be determined by genes or the environment, or more commonly by interactions between them. The genetic contribution to a trait is called the genotype. The outward expression of the genotype is called the phenotype.
Definition from: Talking Glossary of Genetic Terms from the National Human Genome Research Institute
Related discussion in the Handbook
See also Understanding Medical Terminology.