substationPronunciation: /ˈsʌbsteɪʃ(ə)n/Translate substation | into Spanish Definition of substation noun 1a set of equipment reducing the high voltage of electrical power transmission to that suitable for supply to consumers. 2a subordinate station for the police or fire service. North American a small post office, for example one situated within a larger shop. substation in other Oxford dictionaries Definition of substation in the US English dictionary