“创始成员国”常见的英文表达是 “founding member state” 或 “original member state” 。
founding member state： “founding”有“创始的、建立的”意思，“founding member state”直接强调了成员国在组织或机构成立时所扮演的创始角色，是较为常用和正式的表达。
original member state： “original”意为“最初的、原始的”，“original member state”同样传达了成员国在组织创立之初就加入的含义。