Arabic Language Blog

The Arabic Morphological Measure Posted by on Jun 14, 2018 in Grammar, Vocabulary

The Arabic morphological measure المِيْزَان الصَّرْفِي is a measure that is proposed by Arabic grammarians to know and weigh the structure of words. It helps in understanding the internal structure of words, namely knowing whether the constituent letters of a word are essential or additional, and in deriving new words from the same root. The bulk of words in the Arabic lexicon are tri-consonantal (i.e. of three letters). This is known as the root. Therefore, Arabic grammarians proposed a measure of three letters: ف, ع, and ل (فَعَلَ). This post is about the Arabic morphological measure and how it works.

The letters of the Measure:

The reason behind choosing فعل as a measure is two-fold. For one, فعل is an utterance that encompasses all action verbs in Arabic. That is, فَعَلَ ‘to do’ and فِعْل ‘an action’ can replace any verb or verbal noun. Therefore, writing, listening, and sleeping are all أَفْعَال ‘actions’ (plural of فِعْل). Besides, these three letters / sounds represent the three main points of articulations of the Arabic sound system. That is, ف is produced from the front of the mouth, ل is produced from the middle of the mouth, and ع is produced from the back of the mount, the throat.

How It Works with Root Words:

The first letter of a word is called فَاءَ الكَلِمَة ‘the fa’a of the word’; the second letter is called عَيْنَ الكَلِمَة ‘the ‘ain of the word; and the third letter is called لامَ الكَلِمَة ‘the laam of the word.’ For example, in the word كَتَبَ, the كـ is the fa’a of the word فَاءُ الكَلِمَة; ـتـ is the ‘ain of the word عَيْنُ الكَلِمَة; and ـب is the laam of the word لامُ الكَلِمَة, hence كَتَبَ is weighed / measured as فَعَلَ. Diacritical marks are copied from the word to the measure. Similarly, فَهِمَ ‘to understand’ is weighed as فَعِلَ; قُفْل ‘lock’ is weighed as فُعْل; and ضَرْب ‘beating’ is weighed as فَعْل and so forth.

The measure works well and consistently with tri-consonantal root words as each letter in the word is matched with a letter in the measure. If the root word has four essential letters, we add one more laam to the measure. For example, بَعْثَرَ ‘to scatter’ and دَحْرَجَ ‘to roll’ are both weighed as فَعْلَلَ. If the word has five essential letters, we add two more laam to the measure, as in سَفَرْجَل which is weighed as فَعَلَّل (فَعَلْلَل).

How It Works with Complex Words:

A complex word in Arabic is a word (a verb or a noun) that has one, two, or three additional letters. The root of such words is always tri-consonantal. If one letter is added to the tri-consonantal word, the resulting word is called four-letter word كَلِمَة رُبَاعِيَّة; if two letters are added, the new word is called five-letter word كَلِمَة خُمَاسِيَّة; and if three letters are added, the resulting word is called six-letter word كَلِمَة سُدَاسِيَّة.

How It Works with Four-letter Words:

If the additional letter is a repetition (or a geminate) of another letter in the root word, we simply repeat the corresponding letter in the measure. For example, عَلَّمَ ‘to educate’, قَدَّمَ ‘to present, introduce’, and قَطَّعَ ‘to cut into pieces’ are weighed as فَعَّلَ, that is by repeating the ‘ain of the word, عَيْنَ الكَلِمَة. Words like شَدَّدَ ‘to emphasize’, هَدَّدَ ‘to threaten’, and جَلْبَبَ ‘to put a garment on’ are weighed as فَعْلَلَ. To explain, in شَدَّدَ (شَدْدَد), the first letter ش is فَاء الكَلِمَة, the second letter دْ is عَيْنُ الكَلِمَة, the third letter دَ is لامُ الكَلِمَة, and the fourth letter is a repetition of the third, so we add laam to the measure, hence شَدَّدَ = فَعْلَلَ.

If the additional letter is neither essential nor a repetition of the root word; instead, it is a letter of addition, we simply insert it the measure according to its occurrence in the word. For example, in كَاتِب ‘writer’, the root is كتب, and it is measured as فعل. The letter of addition is alif and it occurs after ك (which is the fa’a of the word فَاءُ الكَلِمَة), so we insert it after the ف in the measure, hence كَاتِب is weighed as فَاعِل; مَكْتُوب is weighed as مَفْعُول; مَكْتَب is weighed as مَفْعَل and so forth.

How It Works with five-or-more-letter Words:

The letters of addition in Arabic are ten: أ/ء, ا, ت, س, ل, م, ن, هـ, و, ي. To remember them easily, they are put in the words / phrases: أَمَان وَتَسْهِيْل, هَنَاء وَتَسْلِيْم, or سَأَلْتِمُوْنِيْها. When we weigh a word that has letters of additions, we simply inserted them where they occur in the measure after identifying the root word. For example, in the word اِنْكَسَرَ ‘breaks (by itself)’, the root is كَسَرَ which is weighed as فَعَلَ and the letters of addition are alif and nuun اِنْـ, and they occur before the فَـ, so we insert them before the فـ in the measure, hence اِنْكَسَرَ is weighed as اِنْفَعَلَ. Similarly, اِسْتَغْفَرَ ‘to seek forgiveness’ is weighed as اِسْتَفْعَلَ; قَاَتَلَ ‘to fight one another’ as فَاعَلَ; تَكَلَّمَ ‘to speak’ as تَفَعَّلَ; and so forth.

Additional Notes:

  • All verbs and nouns in Arabic have roots; therefore, they are all weighed.
  • If the word to be weighed has an irregular formation due to a weak letter حَرْفُ العِلَّة that it has, we convert it to its root form before the conjugation. For example, in قَالَ, the alif is not a letter of addition; rather, it is a waw in the root word (which is قَوَلَ); hence, it weighed as فَعَلَ, not فَالَ. So is the case with بَاعَ ‘to sell’, قَامَ ‘stand’, صَامَ ‘to fast’ and so on.
  • If the word to be weighed is a one- letter or two-letter word, it means that a letter or two have been dropped from it, as is with the imperatives قُلْ ‘say!’ from قَالَ, بِعْ ‘sell!’ from بَاعَ and خُذْ ‘take!’ from أَخَذَ. قُلْ is weighed as فَلْ and بِعْ is weighed as فِلْ as the ـعـ of the root has been dropped. خُذْ is weighed as عُلْ as the ف of the root has been dropped. The imperative عِ ‘be aware of!’ is derived from the word وَعَى ‘to become aware of’ which is weighed as فَعَلَ. The first and last letters have been dropped in the imperative, so the remainder is weighed as عِ, and so is the case with قِ ‘guard!’ from وَقَى and فِ ‘pay a debt’ from وَفَى.
  • Knowing the morphological measure helps us derive different types of Arabic words given that Arabic is a derivational language. A typical example of this is the word كَتَبَ in the table above; more than thirty words can be derived from the root كَتَبَ.
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About the Author: Ibnulyemen اِبْنُ اليَمَن

Marhaban! I am from Yemen. I am a language teacher. I teach English and Arabic. In this blog, I will be leading you through Arabic language learning in a sequential fashion. I will focus on Modern Standard Arabic. To learn more, you can also visit my website Ibnulyemen Arabic or my facebook page.


  1. Bob Barker:

    I have tried, and consistently failed, to find information about Arabic “roots for some time.
    Your one blog has clarified so much. Thank you.
    I look forward to future epsiodes.
    I have been an amateur linguist all my adult life.
    My mother tongue is English; I have a fair command of French and German and some knowledge of another half-dozen European languages.
    Now in my mid-eighties I have decided to venture to a different language field and am attempting to teach myself Arabic.
    Thank you again.
    Bob Barker