The three weak letters (حروف العلة) in Arabic are ا (alif), و (waw), and ي (yaa). When any of these letters appears as one of the root letters of a verb, the verb is classified as "weak" (معتل) and undergoes special changes during conjugation that differ from the regular "sound" (صحيح) verb patterns.
Types of Weak Verbs
- Assimilated (المثال): The weak letter is the first root letter (فاء الكلمة). Example: وَعَدَ (he promised) — the و often drops in the present tense: يَعِدُ.
- Hollow (الأجوف): The weak letter is the second root letter (عين الكلمة). Example: قَالَ (he said, from root ق-و-ل) — the middle letter transforms during conjugation.
- Defective (النّاقص): The weak letter is the third root letter (لام الكلمة). Example: دَعَا (he called, from root د-ع-و) — the final letter changes based on the conjugation ending.
Why Weak Verbs Matter
Weak verbs are extremely common in Arabic — many of the most frequently used verbs are weak. Words like قَالَ (said), كَانَ (was), جَاءَ (came), مَشَى (walked), and رَأَى (saw) are all weak verbs. You cannot avoid them, so it is essential to learn their patterns.
The changes that weak letters undergo during conjugation follow consistent rules, even if those rules are more complex than for sound verbs. Our Sarf course dedicates an entire module to weak verbs, with separate lessons for each type. By the end of the module, you will be able to conjugate any weak verb confidently.
A helpful tip: when you encounter a weak verb, first identify which root letter is weak and which type (assimilated, hollow, or defective) it is. This immediately tells you which set of rules to apply for conjugation.