radiationalEnglishOxford New American Dictionaryradiational /ˌrādēˈāSH(ə)nəl, ˌreɪdiˈeɪʃ(ə)nəl / ▸ adjective relating to or involving radiation: heat lost through radiational cooling. – DERIVATIVES radiationally /ˌrādēˈāSH(ə)n(ə)lē, ˌreɪdiˈeɪʃ(ə)n(ə)li / adverb