un·nat·u·ral / ˌənˈnach(ə)rəl/ • adj. contrary to the ordinary course of nature; abnormal: death by unnatural causes. ∎ not existing in nature; artificial: the artificial turf looks an unnatural green. ∎ affected or stilted: the formal tone of the programs caused them to sound stilted and unnatural. ∎ lacking feelings of kindness and sympathy that are considered to be natural: they condemned her as an unnatural woman.DERIVATIVES: un·nat·u·ral·ly adv.un·nat·u·ral·ness n.