Vocabulary What does 双生児 (そうせいじ, souseiji) mean? 双生児 (そうせいじ, souseiji) means twins. Quick factsReadingそうせいじRomajisouseijiPart of speechnoun 双生児そうせいじsouseijitwins1noun twinsKanji in this word双pair, couple生to live, to be born; student児child