(1) The Simple Verb الْفِعْلُ الْمُجَرَّد:

The verbs in (أ) are simple triliteral (three-letter) verbs. Their component letters can include weak letters (i.e. ا, و, ي). Each letter constitutes an integral part of the verb meaning. This kind of verbs make up the bulk of verbs in Arabic language. By adding letters to this type of verbs, many other verbs with various meanings can be derived.

(أ) الْفِعْلُ الثُّلَاثِي the triliteral (three-letter) verb 

كَتَبَ ، قَالَ ، فَتَحَ ، دَعَا ، ضَرَبَ ، جَرَى ، فَرِحَ ، وَعَدَ ، حَفِظَ ، صَامَ ، قَطَعَ ، نَسَى ، سَهَا ، شَرِبَ ، مَنَعَ ، وَجَدَ ، سَاقَ ، سَارَ ، جَرَحَ ، ضِحِكَ ، لَطَمَ ، خَرَجَ ، وَزَنَ ، قَرَأَ ، فَرَشَ ، رَسَمَ ، بَاعَ ، وَقَفَ ، رَعَى ، زَارَ ، قَتَلَ ، غَسَلَ ، خَافَ ، نَثَرَ ، هَزَّ ، طَلَبَ ، سَهِرَ ، طَبَخَ ، شَمَّ ... 

The verbs in (ب) are simple quadriliteral (four-letter) verbs. Like the triliteral, each letter is essential for the verb meaning. This kind of verbs is very limited in Arabic, and they are rarely used.

(ب) الْفِعْلُ الرُّبَاعِي the Quadriliteral (four-letter) verb

زَلْزَلَ ، بَعْثَرَ ، خَلْخَلَ ، زَخْرَفَ ، وَسْوَسَ ، غَرْبَل ، طَأطَأَ ، دَحْرَجَ ، بَلْبَلَ ، حَصْحَصَ

(2) The Complex Verb الْفِعْلُ الْمَزِيْد:

The verbs in (أ) are triliteral complex verbs because their roots comprise only three letters. A letter, two, or three can be added to the root. In the decomposed verbs, the added letters are in orange.

The added letters add more meaning to the root. That is to say, the new meaning is different from that of the root, but it is still related to it. For example, اِسْتَوْقَفَ is from the root وَقَفَ which means 'to stop' while اِسْتَوْقَفَ means 'to request someone to stop'.

(أ) الْفِعْلُ الثُّلَاثِي the triliteral (three-letter) verb 

هَاجَمَ ، اِنْفَعَلَ ، خَمَّنَ ، تَحَدَّثَ ، اِسْتَفْهَمَ ، خَوَّفَ ، اِسْتَقَال ، أَوْجَد ، نَاهَضَ ، اِسْتَوْقَفَ ، اِجْتَمَعَ

← هَجَمَ: هـ + ا + جَمَ = هَاجَمَ

← فَعَلَ: اِنْـ + فَعَلَ = اِنْفَعَلَ

← خَمَنَ: خَمْ + مَ + نَ = خَمَّنَ (خَمْمَنَ)

← وَقَفَ: اِسْتَـ + وَقَفَ = اِسْتَوْقَفَ

The verbs in (ب) are four-letter complex verbs because their roots comprise only four letters. A letter can be added to the root to form new verbs with slightly different meanings. As mentions above, these verbs are few in Arabic, and they are rarely used.

(ب) الْفِعْلُ الرُّبَاعِي the Quadriliteral (four-letter) verb

تَبَعْثَرَ ، تَدَحْرَجَ

← تَـ + دَحْرَجَ = تَدَحْرَجَ

← تَـ + بَعْثَرَ = تَبَعْثَرَ

(1) The Regular Verb الْفِعْلُ الصَّحِيْح:

(A) In (أ), the verbs are composed of three essential letters. If we drop any of the letters, the remaining word becomes meaningless. (B) In (ب), the verbs are composed of four letters. Only three of them are essential as they form the root. The fourth letter is additional. In أَنْزَلَ, for example, the root is نَزَلَ, and the أ is an addition. (C) In (ج), the verbs are composed of five letters. Three of them form the root, and the remainder are additional. In اِجْتَمَعَ, the root is جَمَعَ while the ا and ـتـ are additions. (D) In (د), the verbs are composed of six letters. Three of them are essential, and the remainder are additional. In اِسْتَخْرَجَ, the root is خَرَجَ, while اِسْتَـ are additions. (E) The root of the verbs in (أ), (ب), (ج), and (د) do not include a weak letter (i.e., ا, و, ي), so they are regular verbs. That is, we conjugate them following certain rules and patterns. 

(أ) ثُلاثي three-letter verb:

كَتَبَ ، أَكَلَ ، شَرِبَ ، فَرَّ ، رَسَمَ ، سَأَلَ ، قَرَأَ ، نَصَحَ ، ضَحِكَ ، سَهِرَ ، غَسَلَ ، مَنَعَ ، لَطَمَ ...

(ب) رُبَاعِي four-letter verb:

أَنْزَلَ ، نَظَّفَ ، فَرَّقَ ، وَزَّعَ ، نَزَّلَ ، كَلَّمَ ، أَغْلَقَ ، أَخْبَرَ ، أَكْمَلَ ، فَهَّمَ ، ضَحَّكَ ، أَشْعَلَ ...

(ج) خُمَاسِي five-letter verb:

اِنْكَسَرَ ، تَحَدَّثَ ، اِجْتَمَع ، تَصَوَّرَ ، اِقْتَنَعَ ، تَمَرَّدَ ، اِكْتَشَفَ، تَكَلَّمَ ، اِنْفَجَرَ ، اِشْتَرَكَ ...

(د) سُدَاسِي six-letter verb:

اِسْتَغْفَرَ، اِسْتَخْدَم، اِسْتَخرَجَ ، اِسْتَمَعَ ، اِسْتَقْبَلَ ، اِسْتَعْمَرَ ، اِسْتَثْمَرَ ، اِسْتَوْقَفَ ...

(2) The Irregular Verb الْفِعْلُ الْمُعْتَل:

(A) In (أ), the verbs are composed of three essential letters. If we drop any of the letters, the remaining word becomes meaningless. (B) In (ب), the verbs are composed of four letters. Only three of them are essential as they form the root. The fourth letter is additional. In وَصَّلَ (وَصْصَلَ), for example, the root is وَصَلَ, and the صـْ is an addition. (C) In (ج), the verbs are composed of five letters. Three of them form the root, and the remainder are additional. In تَوَاضَعَ, the root is وَضَعَ while the تَـ and ا are additions. (D) In (د), the verbs are composed of six letters. Three of them are essential, and the remainder are additional. In اِسْتَدْعَى, the root is دَعَى, while اِسْتَـ are additions. (E) The root of the verbs in (أ), (ب), (ج), and (د) includes a weak letter (i.e., ا, و, ي), so they are irregular verbs. That is, conjugating them is not straightforward. 

(أ) ثُلاثي three-letter verb:

وَصَلَ ، صَامَ ، رَمَى ، وَعَد ، جَرَى ، قَالَ ، دَعَا ، وَجَدَ ، زَارَ ، غَزَا ، قَضَى ، خَافَ ...

(ب) رُبَاعِي four-letter verb:

أَوْصَلَ ، وَاعَدَ ، وَصَّلَ ، جَارَى ، أَقَامَ ، أَضَاعَ ، أَوْجَدَ ، أَخَافَ ، قَاضَى ، عَافَى، أَعْطَى ...

(ج) خُمَاِسِي five-letter verb:

تَوَاضَعَ ، تَدَاعَى ،  تَقَاضَى ، تَعَافَى ، اِرْتَمَى ، اِكْتَوَى ، اِنْقَضَى ، اِخْتَارَ ... 

(د) سُدَاسِي six-letter verb:

اِسْتَدْعَى ، اِسْتَقَامَ ، اِسْتَدَارَ ، اِسْتَشَفَى ...

(1) The Intransitive Verb الْفِعْلُ اللَازِم:

These verbs are intransitive because they do not require an object to form a meaningful sentence. In (1), the subject is an attached pronoun ـتُ, ـنَا, ـوا. In (2), the subject is الْأَوْلَادُ. In (3), the subject is الْأُسْرَةُ. In (4), the subject is النَّافِذَةُ. In (5), the subject is اللَّاعِبُونَ. In (6), the subject is الطَّالِبُ. These sentences are meaningful without an object مَفْعُول. The are composed of a verb فِعْل followed by a subject فَاعِل. So, the pattern of these sentences is: Verb فِعْل + Subject فَاعِل. 

جَلَسَ ، قَامَ ، وصَلَ ، ذَهَبَ ، حَضَرَ ، نَام ، تَكَلَّمَ ، اِنْكَسَرَ ، عَصَّبَ ، اِسْتَرَاحَ ، اِنْتَظَر ، تَكَاسَلَ ...

(1) جَلَسْتُ. I sat - جَلَسْنَا. we sat - جَلَسُوا. they sat

(2) اِنْصَرَفَ الْأَوْلَادُ. the boys left

(3) نَامَتِ الْأُسِرَةُ. the family slept

(4) اِنْكَسَرَتِ النَّافِذَةُ. the window broke

(5) اِسْتَرَاحَ اللَّاعِبُونَ. the players rested

(6) تَكَاسَلَ الطَّالِبُ. the student slacked

(2) The Transitive Verb الْفِعْلُ الْمُتَعَدِّي:

These verbs are transitive because they require an object مَفْعُول to make a meaningful sentence. In (1), the subject is تُ, and the object is الْأُسْتَاذَ. In (2), the subject is ـوا, and the object is الْكِتَابَ. In (3), the subject is ـنَا, and the object is الْبَابَ. In (4), the subject is مُحَمَّدٌ, and the 1^st object is عَلِيًّا, and كِتَابًا is the 2^nd object. In (5), the subject is الْأُسْرَةُ, and the object is التِّلْفَازَ. In (6), the subject is سَامُ, and the object is أُخْتَهُ. So, if the object is dropped, the sentence becomes incomplete. If you say شَكَرْتُ, the hearer would ask who. Thus, the pattern in these sentences is: Verb فِعْل + subject فَاعِل + object مَفْعُول. 

شَكَرَ ، ضَرَبَ ، فَهَّمَ ، أَعْطَى ، أَحْضَرَ ، اِسْتَدَعَى ، فَتَحَ ، كَلَّمَ ، شَاهَدَ ، أَخْرَجَ ، اِسْتَخْرَجَ ...

(1) شَكَرْتُ الْأُسْتَاذَ. I thanked the teacher

(2) أَخْرَجُوا الْكِتَابَ. They took out the book

(3) فَتَحْنَا الْبَابَ. We opened the door

(4) أَعْطَى مُحَمَّدٌ عَلِيًّا كِتَابًا. Mohamad gave Ali a book

(5) تُشَاهِدُ الْأُسْرَةُ التِّلْفَازَ. The family is watching TV

(6) ضَرَبَ سَامُ أُخْتَهُ. Sam hit his sister

(1) The Perfective (past) Tense الْفِعْلُ الْمَاضِي:

These verbs are in the perfective (past) form. They express an action that took place in the past. The subject الْفَاعِل of these verbs is an attached pronoun which refers to a noun that is stated before the verb or implied in the context of speaking or writing. For أَنَا, the attached pronoun is تُ. For نَحْنُ, the attached pronoun is نَا. For أَنْتَ, it is تَ. For أَنْتِ, it is تِ. For أَنْتُم, it is تُم. For أَنْتُنَّ, it is تُنَّ. For هُوَ, it is implied (not overt). For هِيَ, it is also implied. With هِيَ, the تْ at the end of the verb is a feminine marker. For هُم, it is وا. For هُنَّ, it is نَ. As you can see from the conjugation, the basic/simple/default form is for the third person masculine singular (i.e., هُوَ). Other forms are derived from it by adding the appropriate pronominal suffix (i.e., attached pronoun) and some changes in diacritics.

(أَنَا ، نَحْنُ ، أَنْتَ ، أَنْتِ ، أَنْتُم ، أَنْتُنَّ ، هُوَ ، هِيَ ، هُم ، هُنَّ)

كَتَبَ: ← كَتَبْتُ ، كَتَبْنَا ، كَتَبْتَ ، كَتَبْتِ ، كَتَبْتُم ، كَتَبْتُنَّ ، كَتَبَ ، كَتَبَتْ ، كَتَبُوا ، كَتَبْنَ

قَالَ: ← قُلْتُ ، قُلْنَا ، قُلْتَ ، قُلْتِ ، قُلْتُم ، قُلْتُنَّ ، قَالَ ، قَالَتْ ، قَالُوا ، قُلْنَ

شَاهَدَ: ← شَاهَدْتُ ، شَاهَدْنَا ، شَاهَدْتَ ، شَاهَدْتِ ، شَاهَدْتُم ، شَاهَدْتُنَّ، شَاهَدَ ، شَاهَدَتْ ، شَاهَدُوا ، شَاهَدْنَ

تَحَدَّثَ: ← تَحَدَّثْتُ ، تَحَدَّثْنَا ، تَحَدَّثْتَ ، تَحَدَّثْتِ ، تَحَدَّثْتُم ، تَحَدَّثْتُنَّ ، تَحَدَّثَ ، تَحَدَّثَتْ ، تَحَدَّثُوا ، تَحَدَّثْنَ

اِسْتَغْفَرَ: ← اِسْتَغْفَرْتُ ، اِسْتَغْفَرْنَا ، اِسْتَغْفَرْتَ ، اِسْتَغْفَرْتِ ، اِسْتَغْفَرْتُم ، اِسْتَغْفَرْتُنَّ ، اِسْتَغْفَرَ ، اِسْتَغْفَرَتْ ، اسْتَغْفَرُوا ، اِسْتَغْفَرْنَ

(1) The Imperfective (present) Tense الْفِعْلُ الْمُضَارِع:

(A) These verbs are in the imperfective (present) form. They express an action that is habitual or happening at the time of speaking. The subject الْفَاعِل  of these verbs is either implicit (covert) or explicit (overt). For أَنَا, it is covert and is inferred from the pronominal prefix أ at the start of the verb. Similarly, it is covert for نَحْنُ and is inferred from the pronominal prefix نَـ. For أَنْتَ, it is also covert and is inferred from the prefix تَـ. For أَنْتِ, أَنْتُم and أَنْتُنَّ, it is an overt suffix, that is ـيْنَ, ـونَ, and ـنْ, respectively. For هُوَ and هِيَ, it is covert. Finally, for هُم and هُنَّ, it is an overt attached pronoun, that is ـونَ and ـنَ, respectively. 

(B) These forms are derived from the root form, that is the third person masculine singular perfective form.

(C) When the subject is overtly stated by a pronominal suffix, the prefix at the beginning of the verb indicates the person, that is second or third person. For example, in تَكْتُبِينَ ، تَكْتُبُونَ ، تَكْتُبْنَ , the تَـ is for second person. In يَكْتُبُ, يَكْتُبُوَنَ, and يَكْتُبْنَ, the يـ is for the third person.

(D) To distinguish between تُشَاهِدُ (هِيَ) and تُشَاهِدُ (أَنْتَ), we have to look at the context.

(أَنَا ، نَحْنُ ، أَنْتَ ، أَنْتِ ، أَنْتُم ، أَنْتُنَّ ، هُوَ ، هِيَ ، هُم ، هُنَّ)

كَتَبَ he wrote:

← أَكْتُبُ ، نَكْتُبُ ، تَكْتُبُ ، تَكْتُبِينَ ، تَكْتُبُونَ ، تَكْتُبْنَ ، يَكْتُبُ ، تَكْتُبُ ، يَكْتُبُونَ ، يَكْتُبْنَ

قَالَ he said:

← أَقُولُ ، نَقُولُ ، تَقُولُ ، تَقُولِينَ ، تَقُولُونَ ، تَقُلْنَ ، يَقُولُ ، تَقُولُ ، يُقُولُونَ ، يَقُلْنَ

شَاهَدَ he watched:

← أُشَاهِدُ ، نُشَاهِدُ ، تُشَاهِدُ ، تُشَاهِدِينَ ، تُشَاهِدُونَ ، تُشَاهِدْنَ ، يُشَاهِدُ ، تُشَاهِدُ ، يُشَاهِدُونَ ، يُشَاهِدْنَ

تَحَدَّثَ he spoke:

← أَتَحَدَّثُ ، نَتَحَدَّثُ ، تَتَحَدَّثُ ، تَتَحَدَّثِينَ ، تَتَحَدَّثُونُ ، تَتَحَدَّثْنَ ، يَتَحَدَّثُ ، تَتَحَدَّثُ ، يَتَحَدَّثُونَ ، يَتَحَدَّثْنَ

اِسْتَغْفَرَ he asked for forgiveness:

← أَسْتَغْفِرُ ، نَسْتَغْفِرُ ، تَسْتَغْفِرُ ، تَسْتَغْفِرِينَ ، تَسْتَغْفِرُونَ ، تَسْتَغْفِرْنَ ، يَسْتَغْفِرُ ، تَسْتَغْفِرُ ، يَسْتَغْفِرُونَ ، يَسْتَغْفِرْنَ