المعنى الاصطلاحي :

Changing the sound of the vowelless letter "noon" or "tanween" (nunation) into the sound of the letter "meem" when followed by the letter "bā", while observing "ghunnah" (nasalization) and "ikhfā’" (slightly hide and lengthen the "noon" sound of the vowelless "noon" and "tanween").

الشرح المختصر :

"Iqlāb" (conversion) is an articulatory characteristic of only the letter "bā" when it comes after "tanween" (nunnation) or a vowelless "noon" in one word or two or following a "tanween". That is because the letter "meem" shares the same point of articulation with the letter "bā", while sharing the "ghunnah" (nasalization) with the letter "noon". The rationale of "iqlāb" is that "izh'hār" (pronouncing the sound of the vowelless "noon" or "tanween" without "ghunnah" or "idghām" or "ikhfā’") would be difficult, since it means that one has to make "ghunnah" (nasalization) in both "noon" and "tanween" and then close the two lips together to articulate the "bā" after "ghunnah". In "mus'hafs" (physical copies of the Qur’an), "iqlāb" is indicated by a small "meem" on top of the "noon" or "tanween". "Iqlāb" has three conditions: 1. Replacing the vowelless "noon" or "tanween" with the pure sound of the letter "meem" in pronunciation rather than writing. 2. "Ikhfā’" (not pronouncing) the "meem" sound when pronouncing the "bā". 3. Making clear "ghunnah" (nasalization) along with "ikhfā’".

التعريف اللغوي المختصر :

"Iqlāb": conversion, exchange. Derived from "qalb", which means turning something from side to side. Other meanings: turning away from, altering.