The word 不可理喻 is formed by sequentially combining the characters 不 (not), 可 (can), 理 (reason), and 喻 (understand). The pair 不可 means "cannot", and 理喻 functions as a verb phrase meaning "to reason with" or "to make understood". Together, they create a literal meaning of "cannot be reasoned with", directly conveying the concept of being unreasonable.