The word Tamyee’ (التمييع) comes from the word Mayya’a (ميع) which means literally to melt as is mentioned in several Arabic Dictionaries. In Mukhtaar As Sihaah, it mentions (ميع السمن) to melt the fat meaning to leave it to run on the earth. Hence, when before the product was solid, due to the process of Tamyee’ (which is the verbal noun or مصدر) it turns into a state of liquid.
As for this terminology when it relates to the Salafi Methodology, it refers to those who soften the methodology of the Salaf by attempting to build bridges between those who adhere to the methodology of the Salaf and those who are deviant. On this juncture it is a must to note that although such a term was not used in the past, it is a correct term to use since it is related to a legislative reality that is present within the Qur’an and the Sunnah in that there are those who accompany the people of innovation, listen to them and excuse them although it is known that doing such actions are prohibited legislatively.
The Mummayi’ is the one who builds such bridges and he is the most dangerous to the people of the Sunnah. This is because he covers the truth with falsehood and decorates it with the latter saying
1. Everybody makes mistakes
2. No one is beyond advice
And other statements which seek to rescue the people of Bid’ah from being refuted.