A cognomen is something like an extra name given to a Roman citizen; it was something personal which functioned a bit like a nickname, but was typically passed from father to son.

姓氏就像给罗马公民的额外名；这个人的名，有像昵，但通亲传给儿子的。

In 160 CE, Julia was born at Emesa, Syria and her cognomen, Domna, means " black" , which has to do with the sun god El-Gabal (Elagabalus) , whose cult stone was black.

公元 160 年，朱莉娅出生在叙利亚的埃梅萨，她的姓 Domna 的意思“黑色”，这与太阳神埃喇伽巴有关，他的崇拜石黑色的。