what is idgamul mutlaq?

Question
what is idgamul mutlaq?

Answer
Idhgaam means merging or insertion of one letter into another.  Mutlaq means absolute; so idgham mutlaq means a complete merging of one letter into the other so that there is nothing remaining of the first letter.  The second letter becomes emphasized with a shaddah to indicate the merging of the first letter into the second.  .