How does the definition softness applies to the running of the sound. In other words, why is it called softness?

As Salam Alikum:

I know the definition of Rikhawa is the "running on of the sound with the letter due to the weakness in the reliance of the articulation point". I understand this definition well but the definition of the name Rikhawa means softness. How does the definition softness applies to the running of the sound. In other words, why is it called softness? 

Thank you so much


Wa alaikum assalaam wa rahmatu Allahi wa barakatuh.

The Arabic language scholars assigned names of characteristics to the Arabic letters many hundreds of years ago, but the name of is very suited for the characteristic of running on of the sound. 

When there is a weakness of the reliance on an articulation point, the letter then is weak in that aspect.  The running of sound in the letters of  is a soft sound and a denotes a weakness in the letter, so it is appropriate.

You are most welcome.