The four-character idiom 不同寻常 (bùtóngxúncháng), meaning "extraordinary" or "out of the ordinary," is formed through a parallel and comparative structure. It literally breaks down into two semantically reinforcing halves: 不同 (bù tóng), meaning "not the same" or "different," and 寻常 (xún cháng), a classical term where both 寻 and 常 individually meant a standard unit of length, together metaphorically meaning "common" or "usual." Thus, the compound directly translates to "not the same as the usual," where the negation of the first part (不同) is applied to the standard described in the second (寻常), creating a unified concept of exceptionality through contrast.