unreasonable and unjust; unconscionable
A yojijukugo describing actions or demands that are both unreasonable and morally wrong. Often used in formal or critical contexts.
His demands are unreasonable and unjust.
I cannot obey such an unconscionable order.
理不尽 focuses on irrationality and unfairness, while 無理非道 adds a stronger moral condemnation of injustice.
不当 means unjust or unfair, often in a legal or procedural sense, but lacks the 'unreasonable' nuance of 無理非道.
A yojijukugo combining 無理 (unreasonable) and 非道 (unjust, inhuman). The exact historical derivation is uncertain, but it likely emerged as a literary or formal compound.