Natural burial grounds. as found in nature and not involving anything made or done by people: 2. Try to be/act natural. Definition of natural adjective in Oxford Advanced Learner's Dictionary. in accordance with human nature: it is only natural to want to be liked. She was adopted immediately after she was born and never knew her natural [= (more commonly) birth] parents. [from 14th c. He is the natural choice to succeed his father as company president. Learn more. In a natural manner; = naturally adv. natural, ingenuous, naive, unsophisticated, artless mean free from pretension or calculation.