Idgham Rules in Tajweed, Explained in Full

What Idgham Means, in General

At its core, idgham is about two neighbouring sounds blending into one rather than being pronounced as two separate, distinct sounds. It happens because certain letter combinations are naturally awkward or unnatural to pronounce fully separately at a normal recitation pace, so the tongue or lips take a smoother path between them instead.

Idgham with Noon Sakinah and Tanween

This is the idgham most students learn first, since noon sakinah and tanween appear constantly. It splits into two types depending on which letter follows.

• Idgham Bighunnah (with nasalisation). Applies before four letters: ya, noon, meem and waw, often remembered through the word "ينمو" (yanmu). The noon sound merges into the following letter while a nasal tone is held.
• Idgham Bilaghunnah (without nasalisation). Applies before two letters: laam and ra. The noon sound merges fully into the following letter with no nasal tone at all.

The Exception Words

There's an important exception: idgham bighunnah only applies across two separate words, not within a single word. A small handful of specific words in the Quran contain a noon sakinah followed by one of the four bighunnah letters within the same word, and in those cases, izhar is used instead, pronounced clearly rather than merged. These exception words come up rarely enough that a teacher will simply flag them the first time you encounter them in the text.

Idgham Shafawi: The Meem Sakinah Version

When a meem sakinah is followed by another meem, the two merge into one, held with a nasal tone, a rule called idgham shafawi. This is covered in full in our Meem Sakinah rules guide, since it sits alongside two other meem-specific rules.

Beyond Noon and Meem: General Merging Rules

Idgham also applies more generally, in a smaller set of specific situations involving other letters entirely, grouped by how closely related the two letters' points of articulation are.

• Idgham Mutamathilain. Two identical letters, the first with no vowel and the second with one, merge into a single, longer sound. For example, a vowel-less ba followed by a ba with a vowel becomes one held ba sound.
• Idgham Mutajanisain. Two different letters that share the same point of articulation but differ in a few characteristics merge into one, for example certain combinations involving ta, tta and dal, which are all produced from a similar position in the mouth.
• Idgham Mutaqaribain. Two letters with points of articulation close to, but not identical to, each other merge in a small number of specific cases, such as certain combinations of qaf and kaf.

Idgham Types at a Glance

Common Mistakes

• Applying bighunnah inside an exception word, merging with a nasal tone where izhar is actually required.
• Adding a nasal tone to bilaghunnah, which should merge with no nasalisation at all.
• Treating all merging rules as identical, when the specific letters involved change how the merge should actually sound.

Because tanween follows the same idgham rules as noon sakinah, our guide to tanween is worth reading alongside this one, as is our iqlab guide, which covers the one noon sakinah rule where the sound changes completely.

How Mariam Quran Tutor Teaches This

Idgham is taught step by step as part of our Tajweed course, starting with the noon sakinah split, then meem sakinah, before touching on the more general merging rules once the basics are solid. For the wider set of rules this connects to, see our Tajweed rules overview. You can book a free trial lesson with no card required to hear this demonstrated properly.