Final answer:
An adaptation is a heritable trait or behavior that helps an organism survive and reproduce in its environment. It can be physical or behavioral and is not constant, changing as the environment changes.
Step-by-step explanation:
An adaptation is a heritable trait or behavior in an organism that aids in its survival and reproduction in its present environment. It is a genetically based characteristic that has evolved because it helps living things survive and reproduce in a given environment. Adaptations can be physical, such as webbed feet for swimming, or behavioral, such as fast speed for catching prey. They are not constant and can change over time as an environment changes.