a familiar name for a person (often a shortened version of a person's given name)
同义词：nicknamemonikersobriquetsoubriquetbyname
the name used to identify the members of a family (as distinguished from each member's given name)
同义词：surnamefamily namelast name
英汉双解大词典
cognomen/kɒɡˈnəʊmɛn/
1.
N（名词）
(originally) an ancient Roman's third name or nickname, which later became his family name 原为古罗马人姓名的第三名字或其绰号，后成为其姓氏 → see also agnomen, nomen, praenomen