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.]
(..) Uncle Jackie was excellent. Fucking guineas. - To Jackie. - Uncle Jackie. Cranberry juice. It's a natural diuretic. My girlfriend drinks it when she's got her period. What, do you got your period? - Fucking...! - Get off! (..)2006 The Departed