العكس: وهو أن يقدم جزءاً في الكلام على جزء آخر ثم يؤخر ذلك المقدم عن الجزء المؤخر أولاً
ʿAks brings one part of an expression before another, then in a corresponding construction places the formerly first part after the other.
It is also called tabdīl. Mere repetition is not its criterion. The effect is the reversal of relative placement that yields a second intelligible construction.
The elements need not be antonyms: a reversal can be produced by interchanging the positions or relationships of otherwise related words.