Weak Verbs in Arabic

In Brief

Arabic verbs whose root contains و or ي often lose or change that letter during conjugation. The position matters: an initial weak letter may disappear (وَصَلَ → يَصِلُ), a middle one may become a long vowel or shorten (قَالَ → قُلْتُ), and a final one changes according to the ending (دَعَا → دَعَوْتُ, مَشَى → مَشَيْتُ). Learn the perfect, imperfect, and command forms together rather than trying to derive every form from one spelling.

Overview

An Arabic verb is usually organized around a root (a set of consonants carrying a broad meaning). A weak verb, فِعْل مُعْتَلّ, has و or ي as one of its root consonants. These two letters can act as consonants, but they also help write long vowels. That double role is why the visible shape of a weak verb changes more than that of a sound verb such as كَتَبَ / يَكْتُبُ “write.”

At B1, the useful goal is not to memorize a single “weak verb ending.” It is to recognize three main families and know where to expect the change. An assimilated verb has a weak first root letter, a hollow verb has one in the middle, and a defective verb has one at the end. “Defective” is only a traditional grammatical label; it does not mean that the verb is incorrect or incomplete.

English changes some common verbs unpredictably—say/said, go/went—but Arabic weak verbs are more systematic. Their spelling can still hide the root: the ا in قَالَ represents a middle weak consonant, and the final ى in مَشَى points back to ي. A dictionary normally gives both the perfect and imperfect citation forms, such as قَالَ، يَقُولُ. Treat that pair as one vocabulary item.

How It Works

The three positions

Type	Weak position	Root	Perfect → imperfect	Main change
Assimilated (مِثَال)	first	و-ص-ل	وَصَلَ → يَصِلُ	Initial و drops in this common Form I pattern
Hollow (أَجْوَف)	middle	ق-و-ل	قَالَ → يَقُولُ	Middle weak radical appears as a long vowel and sometimes shortens
Defective (نَاقِص)	last	د-ع-و	دَعَا → يَدْعُو	Final و changes or disappears before endings
Defective (نَاقِص)	last	م-ش-ي	مَشَى → يَمْشِي	Final ي is written ى in this perfect form and changes before endings

These labels describe the root, not just the letters visible in one form. For example, قَالَ looks as if it contains ا, but its root is ق-و-ل; compare يَقُولُ, قَوْل “saying,” and قُلْتُ “I said.”

Assimilated verbs: the weak letter comes first

In common Form I verbs beginning with root و, the و is present in the perfect but drops from the imperfect. The remaining consonants take the normal imperfect prefixes.

Function	وَصَلَ “arrive”	وَعَدَ “promise”
Perfect, he	وَصَلَ	وَعَدَ
Perfect, I	وَصَلْتُ	وَعَدْتُ
Imperfect, he	يَصِلُ	يَعِدُ
Imperfect, I	أَصِلُ	أَعِدُ
Command, masculine singular	صِلْ	عِدْ
Jussive after لَمْ	لَمْ يَصِلْ	لَمْ يَعِدْ

The perfect remains regular: attach the familiar past-tense suffixes to وَصَلَ. Do not turn “initial و drops” into a rule for every tense, every pattern, or every initial-weak root. Some verbs preserve it, and initial ي does not automatically behave like the common وَصَلَ / يَصِلُ pattern. The safest vocabulary entry is therefore وَصَلَ، يَصِلُ, not وَصَلَ alone.

Hollow verbs: the weak letter comes in the middle

A hollow verb usually has a long vowel in forms such as قَالَ “he said,” قَالَتْ “she said,” and قَالُوا “they said.” With the past-tense endings used in قُلْتُ “I said,” قُلْنَا “we said,” and قُلْنَ “they (feminine) said,” that long vowel shortens. Notice that third-person feminine قَالَتْ keeps the long vowel; it belongs with the unshortened forms. The replacement short vowel is not identical in every hollow verb, so learn the first-person perfect as a useful third principal part.

Person	Perfect of قَالَ	Meaning
أَنَا	قُلْتُ	I said
نَحْنُ	قُلْنَا	we said
أَنْتَ / أَنْتِ	قُلْتَ / قُلْتِ	you said
أَنْتُمَا	قُلْتُمَا	you two said
أَنْتُمْ / أَنْتُنَّ	قُلْتُمْ / قُلْتُنَّ	you all said
هُوَ / هِيَ	قَالَ / قَالَتْ	he/she said
هُمَا	قَالَا / قَالَتَا	they two said
هُمْ / هُنَّ	قَالُوا / قُلْنَ	they said

The imperfect has يَقُولُ when no ending forces shortening. Forms such as تَقُولِينَ “you (f.) say” and يَقُولُونَ “they say” keep the long vowel. With a consonantal ending, it shortens: هُنَّ يَقُلْنَ “they (f.) say.” It also shortens when the final consonant must become vowelless in the jussive (a verb form used after particles such as لَمْ) and in the command:

Environment	Form	Meaning
Indicative	يَقُولُ	he says
After لَنْ	لَنْ يَقُولَ	he will not say
After لَمْ	لَمْ يَقُلْ	he did not say
Command	قُلْ	say!

Other hollow verbs may use a different short vowel: نَامَ، يَنَامُ، نِمْتُ، نَمْ “sleep,” and بَاعَ، يَبِيعُ، بِعْتُ، بِعْ “sell.” This is why copying قُلْتُ mechanically onto every hollow verb fails.

Defective verbs: the weak letter comes last

A final weak radical is exposed when a suffix follows it. Compare a root ending in و, د-ع-و, with one ending in ي, م-ش-ي.

Person or form	دَعَا “call, invite”	مَشَى “walk”
he, perfect	دَعَا	مَشَى
she, perfect	دَعَتْ	مَشَتْ
I, perfect	دَعَوْتُ	مَشَيْتُ
we, perfect	دَعَوْنَا	مَشَيْنَا
they (m./mixed), perfect	دَعَوْا	مَشَوْا
he, imperfect	يَدْعُو	يَمْشِي
you (f.), imperfect	تَدْعِينَ	تَمْشِينَ
they (m./mixed), imperfect	يَدْعُونَ	يَمْشُونَ

Notice three particularly useful facts. First, the final radical returns clearly in دَعَوْتُ and مَشَيْتُ. Second, before تْ it disappears: دَعَتْ, مَشَتْ. Third, both verbs have ـَوْا in the third-person masculine plural perfect: دَعَوْا, مَشَوْا. The final ا there is an orthographic separator written after the group و; it is not pronounced as a separate long vowel.

Mood also affects a defective imperfect verb. The subjunctive (a form required after particles such as لَنْ) has a final fatḥa, while the jussive deletes the final weak letter:

Environment	و-final root	ي-final root
Indicative	يَدْعُو	يَمْشِي
After لَنْ	لَنْ يَدْعُوَ	لَنْ يَمْشِيَ
After لَمْ	لَمْ يَدْعُ	لَمْ يَمْشِ
Command, masculine singular	اُدْعُ	اِمْشِ
Command, feminine singular	اُدْعِي	اِمْشِي
Command, masculine plural	اُدْعُوا	اِمْشُوا

In ordinary unvowelled text, several distinctions become invisible. يدعو can display the same consonantal spelling in indicative and subjunctive contexts; the preceding particle and the sentence structure tell you how to read it.

A practical learning formula

For each new weak verb, record at least these forms:

1. third-person masculine perfect: قَالَ;
2. third-person masculine imperfect: يَقُولُ;
3. first-person perfect when the stem changes: قُلْتُ;
4. masculine singular command when common: قُلْ.

For a defective verb, also record the root or a suffixed form: مَشَى، يَمْشِي، مَشَيْتُ. This makes the hidden final ي easier to remember.

Examples in Context

Arabic	English	Note
وَصَلَ القِطَارُ مُبَكِّرًا.	The train arrived early.	Assimilated verb; و appears in the perfect.
يَصِلُ القِطَارُ عِنْدَ السَّاعَةِ الثَّامِنَةِ.	The train arrives at eight o’clock.	Initial و drops in يَصِلُ.
لَمْ يَصِلْ رَدُّهَا بَعْدُ.	Her reply has not arrived yet.	Jussive after لَمْ.
وَعَدْتُهُ أَنْ أُسَاعِدَهُ.	I promised him that I would help him.	The perfect keeps initial و.
قَالَتْ لِي الحَقِيقَةَ.	She told me the truth.	Hollow long vowel remains before تْ of “she.”
قُلْتُ لَهُ الحَقِيقَةَ.	I told him the truth.	The hollow vowel shortens before تُ.
لَمْ يَقُلْ أَحَدٌ شَيْئًا.	Nobody said anything.	يَقُولُ shortens after لَمْ.
قُلْ مَا تُرِيدُ بِوُضُوحٍ.	Say what you want clearly.	Masculine singular command.
دَعَوْنَا أَصْدِقَاءَنَا إِلَى العَشَاءِ.	We invited our friends to dinner.	Final root و appears before نَا.
هِيَ تَدْعُو إِلَى التَّغْيِيرِ.	She is calling for change.	Defective imperfect in ـُو.
لَمْ يَدْعُهُمْ إِلَى الاِجْتِمَاعِ.	He did not invite them to the meeting.	Final weak letter drops after لَمْ.
مَشَيْتُ إِلَى العَمَلِ صَبَاحًا.	I walked to work in the morning.	Final root ي appears before تُ.
يَمْشِي الأَطْفَالُ إِلَى المَدْرَسَةِ.	The children walk to school.	Defective imperfect in ـِي.
اِمْشِ بِبُطْءٍ، مِنْ فَضْلِكَ.	Walk slowly, please.	Masculine singular command ends in kasra.

Common Mistakes

Keeping the initial و in the common imperfect pattern

• Wrong: هُوَ يَوْصِلُ غَدًا when you mean “he arrives tomorrow.”
• Right: هُوَ يَصِلُ غَدًا.
• Why: In وَصَلَ، يَصِلُ, the root و drops in the Form I imperfect. يُوصِلُ is a different derived verb meaning “he delivers/takes someone.”

Keeping the long vowel before a consonantal past suffix

• Wrong: قَالْتُ ذَلِكَ.
• Right: قُلْتُ ذَلِكَ.
• Why: The long middle vowel of قَالَ shortens before ـتُ. Learn قَالَ، يَقُولُ، قُلْتُ as a set.

Using the dictionary spelling before every ending

• Wrong: مَشَىتُ إِلَى البَيْتِ.
• Right: مَشَيْتُ إِلَى البَيْتِ.
• Why: The final ى is not simply retained before the suffix. The underlying ي appears in مَشَيْتُ.

Forgetting deletion after لَمْ

• Wrong: لَمْ يَدْعُو أَحَدًا.
• Right: لَمْ يَدْعُ أَحَدًا.
• Why: لَمْ requires the jussive, and a final weak letter is deleted in this form.

Assuming every weak verb chooses the same short vowel

• Wrong strategy: Building نُمْتُ from نَامَ because قَالَ gives قُلْتُ.
• Right: نِمْتُ “I slept,” but قُلْتُ “I said.”
• Why: Hollow verbs belong to different vowel classes. The perfect–imperfect pair and first-person perfect must be learned with the verb.

Usage Notes

Weak-verb alternations belong to Modern Standard Arabic and are visible in careful speech, news, formal writing, and literature. Fully vowelled examples make the patterns clearer, but everyday Arabic writing normally omits most short-vowel marks. Readers therefore rely on the particle, the subject ending, and knowledge of the verb: لم يقل is read لَمْ يَقُلْ, not as the ordinary indicative يَقُولُ.

Spoken Arabic varieties also have weak verbs, but their vowels and some endings differ from Modern Standard Arabic. A dialect may pronounce or simplify forms in ways not shown in these tables. If your immediate goal is conversation in one variety, learn its forms separately rather than mixing a dialect pronunciation into a Standard Arabic paradigm.

The terms assimilated, hollow, and defective are useful dictionary and classroom labels. In real reading, recognition matters more than naming: see قُلْتُ, connect it with قَالَ, and understand the sentence. Naming the class is a tool for predicting forms, not the final learning goal.

Beyond the Basics / Advanced Use

The three classes can overlap. A verb with two weak root consonants is sometimes called doubly weak or لفيف. For example, وَفَى has weakness at both the beginning and end. Such verbs combine processes, so it is better to learn their principal forms individually than to stack beginner rules mechanically.

Derived verb patterns can also preserve or reshape weak radicals differently from Form I. Compare root و-ص-ل in وَصَلَ / يَصِلُ “arrive” with Form II وَصَّلَ / يُوَصِّلُ “deliver” and Form IV أَوْصَلَ / يُوصِلُ “bring or deliver.” Hollow roots appear in forms such as أَقَامَ / يُقِيمُ “establish; stay,” from ق-و-م. The pattern itself now helps determine the surface form; the simple rule “drop initial و” no longer applies.

Defective verbs show further changes when imperfect endings lose ن in the subjunctive or jussive. The indicative أَنْتِ تَدْعِينَ becomes لَنْ تَدْعِيَ and لَمْ تَدْعِي; هُمْ يَدْعُونَ becomes لَنْ يَدْعُوا and لَمْ يَدْعُوا. Here two systems interact: the weak final root and the endings of the so-called “five verbs.” Context and particles are especially important because unvowelled spellings may look alike.

Finally, و or ي in the written word does not by itself prove that a verb is weak in the relevant position. Analyze the root and compare related words. Conversely, the weak radical may be hidden behind ا or ى. Root awareness becomes increasingly valuable when using an Arabic dictionary and when meeting verbal nouns and participles (verb-based words such as “saying” or “seller”).

Practice Tips

1. Make four-form cards. Write قَالَ – يَقُولُ – قُلْتُ – قُلْ on one card, then do the same for five frequent hollow verbs. Saying the forms aloud helps the vowel alternation become automatic.
2. Sort by weak position. Take new verbs from a short text and mark the weak radical as first, middle, or final. Then predict one changed form before checking a dictionary.
3. Drill trigger pairs. Contrast يَقُولُ / لَمْ يَقُلْ, يَدْعُو / لَمْ يَدْعُ, and يَمْشِي / لَمْ يَمْشِ. This trains you to notice both the particle and the stem change rather than reading each word in isolation.

Related Concepts

• Prerequisite: Past Tense (Perfect) — review the regular suffixes first, because weak verbs use the same person endings while adjusting their stems.