The ten verb forms

A grid of ten classical patterns, each twisting the meaning of the root in a predictable way. Once you see it, half of Arabic vocabulary becomes guessable.

Arabic verbs are organized into a system of ten patterns, called Forms I through X by Western grammarians. Each pattern takes a three-letter root and adds a fixed set of prefixes, doubled letters, or extra vowels — and each pattern shifts the meaning of the root in a recognisable direction. Form II tends to be intensifying or causative. Form III is reciprocal or directed-at. Form VII is passive or reflexive. Form X is to ask for something or to consider it as such. Once you know the patterns, you can often guess what a new verb means just by recognising its shape.

The pattern table

Using the dummy root f-ʿ-l, the ten forms in their past-tense citation shape are:

Form I — base

فَعَلَ faʿala

The simple, basic verb. Carries the core meaning of the root.

Form II — doubled middle

فَعَّلَ faʿʿala

Causative or intensive. To make someone do, or to do something thoroughly.

Form III — long aa after first letter

فاعَلَ faaʿala

Reciprocal or directed at someone. To do with or to.

Form IV — alif prefix

أَفْعَلَ afʿala

Causative. Often parallel to Form II in meaning, but with different roots.

Form V — ta- prefix on Form II

تَفَعَّلَ tafaʿʿala

Reflexive or passive of Form II. To become / to do to oneself.

Form VI — ta- prefix on Form III

تَفاعَلَ tafaaʿala

Reciprocal among multiple parties. To do with each other.

Form VII — in- prefix

اِنْفَعَلَ infaʿala

Passive or middle. To get / become done.

Form VIII — t infixed

اِفْتَعَلَ iftaʿala

Reflexive, often with a sense of doing for oneself or undertaking.

Form IX — doubled final, for colors and defects

اِفْعَلَّ ifʿalla

Rare. To become a color or to acquire a defect.

Form X — ista- prefix

اِسْتَفْعَلَ istafʿala

To ask for, seek, or consider something as. Highly productive in modern Arabic.

Forms I through X cover almost all verbs you will see. Forms beyond X (XI–XV) exist in classical grammar but are obscure and rarely encountered. Not every root appears in every form — most roots are used in only three or four — but each form has a stable enough meaning that meeting an unfamiliar verb in a familiar form is usually decipherable.

The k-t-b root through several forms

The root ك ت ب (writing) is one of the few that runs through many forms. Watch the meaning twist with the pattern.

to write (Form I)

كَتَبَ kataba

to dictate (Form II)

كَتَّبَ kattaba

"To make someone write."

to correspond with (Form III)

كاتَبَ kaataba

"To write back and forth with."

to dictate / to give to write (Form IV)

أَكْتَبَ aktaba

to subscribe / to enroll (Form VIII)

اِكْتَتَبَ iktataba

"To write oneself in" — to register, subscribe.

to ask someone to write / to dictate to (Form X)

اِسْتَكْتَبَ istaktaba

"To request writing." Form X is the "ask for X" pattern.

Notice how Form X — istafʿala — keeps showing up to mean "ask for / seek." From the root ʿ-l-m ("knowing") it gives istaʿlama, "to inquire, to ask for information." From kh-d-m ("serving") it gives istakhdama, "to use, to put into service." From q-b-l ("receiving") it gives istaqbala, "to welcome, to receive." Once you spot the ista-, you can guess.

Form II and its causative cousins

Form II — doubling the middle root letter — is one of the most productive in modern Arabic. It often turns an intransitive verb into a transitive one, or intensifies an action.

to learn (Form V)

تَعَلَّمَ taʿallama

to teach (Form II)

عَلَّمَ ʿallama

Form II is the causative of "to know" — to make someone know.

to know (Form I)

عَلِمَ ʿalima

to inform (Form IV)

أَعْلَمَ aʿlama

Another causative pattern from the same root.

Why English speakers find this hard — and very rewarding

Hard, because it is unlike anything English does. English has prefixes (un-, re-, dis-) and suffixes (-ize, -ify) that twist meaning, but they are bolt-ons. Arabic verb forms are ten distinct skeletons, each requiring its own conjugation pattern, its own active and passive participles, its own verbal noun.

Rewarding, because once internalised, the system multiplies your vocabulary. Knowing one root and the meanings of the ten forms gives you potentially ten verbs, plus their participles and verbal nouns — a few dozen words for the price of one. It is the closest thing in language to compound interest.

Verbal nouns and participles

Each form has a characteristic verbal noun (maSdar) and a characteristic active and passive participle. Forms II–X have predictable verbal nouns; Form I's verbal noun is unpredictable and must be learned with the verb. Some examples:

teaching (verbal noun of Form II)

تَعْليم taʿliim

use, employment (verbal noun of Form X)

اِسْتِخْدام istikhdaam

teacher (active participle of Form II)

مُعَلِّم muʿallim

All Form II participles start with mu-, with the shape muCaCCiC.

user (active participle of Form X)

مُسْتَخْدِم mustakhdim

Form X participles all start with musta-.

What it's called in the Arabic tradition

Form I is الفِعْل المُجَرَّد (al-fiʿl al-mujarrad, "the bare verb") — the unaugmented base. Forms II–X are collectively الأَفْعال المَزيدَة (al-afʿaal al-maziida, "the augmented verbs"). Each form is identified by its wazn (pattern), so a teacher will say a verb is "on the wazn of istafʿala" rather than calling it "Form X." See roots and patterns for the broader system this fits into.