Definition of unnaturalism in English:
unnaturalism
noun (ˌ)ʌnˈnatʃ(ə)r(ə)lɪz(ə)m(ˌ)ʌnˈnatʃ(ə)rəlɪz(ə)m
Belief in, or representation of, the unnatural.
Origin
Mid 18th century; earliest use found in William Warburton (1698–1779), bishop of Gloucester and religious controversialist. From unnatural + -ism.