The definition of tafkheem: Fattening

Its applied definition:  It is a heaviness that enters the body of the letter, so that the mouth is filled with its reverberation (echo). The method of making a letter have the characteristic of tafkheem is: elevating the posterior tongue to the roof of the mouth (soft palate), creating more space between the roof of the mouth and the bottom of the mouth, and focusing the pressure of the letter to the roof of the mouth.

The linguistic definition of tarqeeq : Thinness

Its applied definition:  It is a thinness that enters the body of the letter, so the mouth is not filled with its reverberation (echo).

The Arabic letters are divided into three groups as to tafkheem and tarqeeq:

        1.   Letters that always have tafkheem.  These are the seven letters in the group .  They are also called the tafkheem letters.

        2.   Letters that have tafkheem sometimes and tarqeeq other times. 

                          a)   The lengthened alif.

                          b)   The  in the Glorious name of    .

                          c)   The   

         3.  Letters that always have tarqeeq.  This group consists of the rest of the Arabic alphabet. 

The Letters That Always Have Tafkheem  

The seven letters of   group make up this category.  The letters of  are
  .  These letters do not all have the same degree if tafkheem, instead there are differences according to the letter’s characteristics, and the strength or weakness of these characteristics.  Every time a letter has a strong characteristic, its tafkheem is stronger.   letters ( ) are stronger in tafkheem than the rest of letters due to the adhesion of the tongue to the roof of the mouth in conjunction with the elevation of the tongue.  The ranking of letters from strongest is  then , then , then , then , then , then

Levels of Tafkheem

There are two different schools of thought when it comes to tafkheem.  Both are correct, but the reader should follow one or the other in their reading. 

Three Levels of Tafkheem

This school of thought has three different levels in tafkheem.  The strongest being the tafkheem letter that has a fat-h, the second being the tafkheem letter with a dhammah, and the third level, the tafkheem letter with a kasrah.  The saakin tafkheem letter follows the level of tafkheem of the vowel on the letter before it.  This means if the tafkheem letter is saakin, and the letter before it has a fat-ha, then the tafkheem letter will be at the highest level of tafkheem (as the  in:  ) . The saakin letter of tafkheem preceded by a dhammah would have the second level of tafkheem (as the  in :  .  The saakin tafkheem letter preceded by a kasrah is at the lowest level of tafkheem (such as the  in :  .  Sheikh Mohammed Al-Mutawali described these levels in the following lines:

(Then the heavy ones come
with three levels and they are

The one with a fath, then the dhammah, then the kasrah,
 and the saakin follows what preceded it

So what came before it in a vowel,
then assume for it as a harakah that vowel.)

The Five Levels of Tafkheem

The second school of thought of tafkheem has five levels.  The highest level being a tafkheem letter being followed by a long alif (for example the  in:  ). The second level is a tafkheem letter with a fathah on it (such as the  and  in:  ). The next level that of a tafkheem letter having a dhammah (as in  ).   The next level is a tafkheem letter with a sukoon (for example  ). And the last level, that of a tafkheem letter with a kasrah (such as the  in:    ). This school of thought as to tafkheem varies from the previous three level school in a few ways.  First, the tafkheem letter with a fathah has two categories, that of a fath followed by an alif, and then a fathah not followed by an alif.  This school also varies from the previous one in that the tafkheem letter with a sukoon has its own level of tafkheem, whereas the other school of thought has the saakin letter following the tafkheem level of the vowel on the letter preceding it. This means that there will be a difference of tafkheem between the saakin letters in this group, which are not affected by the vowel of the letter preceding it, and the other group which is totally affected by the vowel on the letter preceding it.  For example, a saakin tafkheem letter preceded by a fathah in the three level school of thought, will have the highest ranking of tafkheem, whereas a saakin tafkheem letter of this five level school of thought, will have the 4th degree of tafkheem. Ash-Sheikh Al-Mutawali described the five levels of tafkheem in the following lines:

(and it is said, no the one with the fat-hah followed by an alif 
and after it a fat-hah without an alif

the one with the dhammah, the saakin, the one with the kasrah;
so that is five, its mention came to you.

and if it is in the lowest level
It has tafkheem, cut off from the istifaal (lowering of the tongue)
So it cannot be said it has tarqeeq              
Like its opposite, that is the truth.  

Next tidbit lesson, insha' Allah will continue with  tafkheem and tarqeeq, moving on to explain the letters that sometimes have tafkheem and sometimes tarqeeq.