je ne sais quoi(n.)
"无法表达的某种东西",源自法语,字面意思是"我不知道什么"。
[T]hey are troubled with the je-ne-scay-quoy, that faign themselves sick out of niceness but know not where their own grief lies, or what ayls them. [Thomas Blount, "Glossographia," 1656]
“他们被 je-ne-scay-quoy 困扰着,这些人因过于讲究而假装生病,但不知道他们自己的悲痛在哪里或者他们犯了什么病。” [托马斯·布朗特(Thomas Blount),《字汇学》,1656]