由よしなき

Meanings

pre-noun adjectival

Literary pre-noun adjectival (rentaishi) meaning something is without reason, groundless, or pointless. Often used in formal or written contexts.

由よしなき噂うわさに惑まどわされてはいけない。
Don't be misled by groundless rumors.
彼かれの怒いかりは由よしなきものだった。
His anger was senseless.

Kanji

由wherefore, a reason
無nothingness, none, ain't

Related words

無む意い味み
無意味 is a common noun/adjectival noun meaning 'meaningless', while 由なき is a literary pre-noun adjectival with a nuance of 'groundless' or 'without reason'.
理り不ふ尽じん
理不尽 means 'unreasonable' or 'irrational', often implying unfairness, whereas 由なき focuses on the lack of basis or justification.

Written forms

由よしなき
Standard kanji-kana mixed spelling for this pre-noun adjectival.
由よし無なき
Alternate spelling using 無 for the negative element; less common than 由なき.

Etymology

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.