HYPAETHRAL Meaning of HYPAETHRAL in English [ hʌɪ'pi:θr(ə)l , hɪ- ](also hypethral ) ■ adjective (of a classical building) having no roof.OriginC18: via L. from Gk hupaithros (from hupo 'under' + aithēr 'air') + -al . Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004