pre-noun adjectival
indescribable; inexpressible; unspeakable
Used before nouns to describe something so profound, emotional, or vague that it cannot be put into words. Often found in literary or emotional contexts.
言い知れぬ不安に襲われた。
I was seized by an indescribable anxiety.
彼の言葉には言い知れぬ魅力がある。
His words have an inexpressible charm.
From the negative form of the classical verb 言い知る (to know by speaking), literally 'cannot be known through words'. The modern form is a fixed pre-noun adjectival.