un·ut·ter·a·ble
adjective/ʌnˈʌtərəbl/
/ʌnˈʌtərəbl/
[only before noun] (formal)- used to emphasize how great a particular emotion or quality is
难以言表的；说不出的 - unutterable sadness
无法形容的悲伤 - He felt such an unutterable fool.
他觉得自己真是一个难以形容的傻瓜。
- unutterable sadness