pre-noun adjectival
meaningless; senseless; absurd
Literary pre-noun adjectival (rentaishi) meaning something is without reason, groundless, or pointless. Often used in formal or written contexts.
Don't be misled by groundless rumors.
His anger was senseless.
Standard kanji-kana mixed spelling for this pre-noun adjectival.
Alternate spelling using 無 for the negative element; less common than 由なき.
Composed of 由 (reason, cause) + なき (classical negative form of ある, 'to be'), literally 'without reason'. The form is a fossilized classical construction used as a pre-noun adjectival.