Shiddah actually means strength. Its implemented definition is that the sound is imprisoned when declaring these letters. Its letters are found in the order. The reason that the sound is imprisoned is due to the secure connection of these letters upon their makhraj.
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The reverse of shiddah is rikhwah or rakhāwah. It means softness. The sound flows when pronouncing the letters of rikhwah. The purpose of why sound flows when marking these letters is because of the weak dependence of these letters upon their makhraj muqaddimah al jazariyyah.
In the other half of this line, the letters are addressed. Which literally means to raise. Therefore Ibn al jazariyyah refers to them as the seven elevated letters that are opposite to the third attribute mentioned in the first line, istifāl. Its applied definition is the rising of the back portion of the tongue when pronouncing these letters.
Due to the back portion of the tongue rising, these letters are read with a full/thick sound Called tafkhīm.
Its inverse is istifāl, which really means to lower. Its completed definition is when the back part of the tongue does not rise but instead lays deep when pronouncing these letters. It is found in all the letters beside the letters of isti˘lā`. Due to the back portion of the tongue lying low, these letters are addressed with a flat/thin sound (tarqīq).
The first property mentioned in this line is hams, which is the difference between the first attribute specified in the previous line, Jahr.
Hams intends to whisper. Its applied definition is the flowing of the breath when pronouncing these letters tajweed. The letters of hams are ten and found in the combination of breath flows so smoothly in these letters is because the dependence of these letters upon their makhraj Quran poem is weak, which allows the breath to flow. Thus, these letters are smoother in their pronunciation in comparison with their opposite letters which have Jahr.
The opposition of hams is Jahr, which indicates bright or loud. Its applied definition is the imprisonment of breath when pronouncing these letters. The letters of Jahr are all the unused letters of the Arabic alphabet besides the ten letters of hams.
The purpose why breath is imprisoned in these letters is that they have a strong belief upon their makhraj, which does not allow the breath to flow. Therefore these letters are usually louder than in the letters of hams. The next attribute mentioned is shiddah, which is the reverse of the second attribute specified in the first line, rikhwah, tuhfat al atfal.