He died of 'natural causes'. [=he died because he was ill or old and not by being killed in an accident, battle, etc.]
She was adopted immediately after she was born and never knew her 'natural' [=(more commonly) 'birth'] parents.
a country rich in 'natural resources' [=a country that has many valuable plants, animals, minerals, etc.]
(..) - She's nice. But look at him. You gotta let that guy go, just out of your brain and move on. I know you need to grieve a relationship. It's only natural. Okay. You wait here. I'm going to go smell him. No, no, no. Sweetie. You're not allowed to smell teenagers. (..)2009 17 Again