King James Dictionary 
1. According to nature by the force or impulse of nature not by art or habit. We are naturally prone to evil. 2. According to nature without affectation with just representation according to life. 3. According to the usual course of things as, the effect or consequence naturally follows. 4. Spontaneously without art or cultivation. Every plant must have grown naturally in some place or other.
Webster's Dictionary 
(adv.) In a natural manner or way; according to the usual course of things; spontaneously.