Answer: intrinsic

AnswerCrossword Clue
INTRINSICNative
INTRINSICBelonging by its very nature
INTRINSICReal
INTRINSICEssential
intrinsic(of a muscle) Contained wholly within the organ on which it acts
intrinsicBelonging naturally; essential
intrinsicinward, internal also INTRINSICAL