The word "Idghaam" means merging.

​

The following six letters are called Huroof Idghaam (Merging letters):

​

          ي  ر  م  ل  و  ن

​

These letters are collectively pronounced يرملون , which causes the name, Idghaam of Yarmaloon.

​

1. Whenever any of the Huroof Idghaam letters comes after Noon Sakin or Tanween, the letter will always have a Tashdeed.

​

2. If Raa or Laam come after Noon Sakin or Tanween, then Idghaam will be read without Ghunnah.

​

3.If the remaining letters (or "Yanmu" ينمو ) comes after Noon Sakin or Tanween, then Idghaam will be read with Ghunnah.