Cognomen Siyun (Siyun 
, 四云 , 斯韵 ) , across the world, is a rare family name. The family name Siyun is habitual in Singapore, where it is a rare surname, China, where it is a very rare surname, and Malaysia. Measured by absolute frequency, this name is the most popular in China, Indonesia, and Singapore. More frequently, Siyun is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Siyun | Indonesia, China, South Korea, United States, Myanmar |
| 四云, 思蕴, 斯韵 | China |
Сийун, Сиюн, Сиюнь, Сіюн, Сіюнь, ស៊ីយូន, シユン, 丝云, 丝允, 丝芸, 丝蕴, 丝韵, 厶允, 厶奫, 司云, 司允, 司昀, 司蕴, 司赟, 司韵, 嗣云, 嗣允, 嗣昀, 嗣芸, 嗣贇, 嗣赟, 嗣运, 嗣鋆, 嗣韫, 嗣韵, 四允, 四芸, 四运, 寺云, 巳云, 巳昀, 巳赟, 思云, 思允, 思匀, 思妘, 思昀, 思晕, 思沄, 思耘, 思芸, 思蒀, 思蘊, 思贇, 思赟, 思运, 思郓, 思郧, 思酝, 思鋆, 思陨, 思雲, 思韫, 思韵, 思韻, 斯云, 斯允, 斯匀, 斯昀, 斯晕, 斯沄, 斯芸, 斯蕴, 斯贇, 斯赟, 斯鈗, 斯鋆, 斯韫, 楒雲, 泗云, 泗允, 澌韵, 祀云, 祀运, 私云, 絲韻, 肆云, 肆雲, 虒云, 西云, 西允, 西昀, 西芸, 西蕴, 西赟, 西运, 西鋆, 西韫, 西韵, 锡云, 锡允, 锡恽, 锡昀, 锡晕, 锡沄, 锡耘, 锡芸, 锡蕴, 锡贇, 锡赟, 锡运, 锡鋆, 锡韵, 锶云, 锶蕴, 锶韵, 飔云, 驷云, and 시윤