1.AdjectiveOf, pertaining to, characterized by or showing adaptation; making or made fit or suitable.
"The National Highway Traffic Safety Administration says it issued a final rule allowing what’s called “adaptive driving beam headlights” on new vehicles. It will go into effect when published in the Federal Register in the next few days."
2.AdjectiveCapable of being adapted or of adapting; susceptible of or undergoing accordant change.
3.AdjectiveOf a trait: that helps an organism to function well in its environment.
4.AdjectiveOf a trait: that helps a person to function well in society.