DECAGON Meaning of DECAGON in English [ 'dɛkəg(ə)n ]■ noun a plane figure with ten straight sides and angles.Derivatives~al adjective OriginC17: via med. L. from Gk dekagōnon , neut. of dekagōnos 'ten-angled'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004