In the biological context the adaptation means to change in a such that a way that helps in the survival.
In extreme cases or normal cases where the survival of organism is not possible without changing their body is known as adaptation.
This is so because this enables the survival of organism. By certain modification in the body in order to survive in the condition is what adaptation is.
so, biologically it is a mode to make life simpler by changes in the genes which leads to certain changes in the body of the organism to help in survival.
process by which an animal or plant species becomes fitted to its environment; it is the result of natural selection's acting upon heritable variation. ... Adaptation refers to the ability of cells to adjust to severe stresses and achieve altered
