In Arabic, there are 10 verb forms that can be formed from each root. The root usually consists of 3 letters, and verb forms are made up of different patterns involving a given root. Some forms are used for a given root while others are not. Verb forms are usually indicated by roman numerals in English.
Form I (يَفعلُ/فعلَ) is the most basic form of the verb; it consists of the 3-lettered root only, e.g. (عمل) worked, (حمل) carried, (درس) studied, (قطع) cut. All verb forms of a given root are usually related to the root in form and meaning. They should have the 3 letters of the root in their form, and they should have the basic meaning of the root in addition to some other predictable senses.
درست منى الكيمياء في الجامعة.
“Mona studied Chemistry at university.”
يعمل أبي في شركة حكومية.
“My father works in a governmental company.”
Form IIفعّل/يفعِّلُ) ) usually makes a verb transitive, e.g. (درس) studied and (درّس) taught; (حمل) carried and (حمّل) loaded. It also serves to make the action seem more intense, e.g. (قطع) cut and (قطّع) chopped, (كسر) broke and (كسّر) smashed.
درسّت منى الكيمياء في الجامعة.
“Mona taught Chemistry at university.”
Form III (فاعل/يفاعِلُ) sually indicated participation, i.e. the action is done by more than one participant, e.g. (شارك) shared; (راسل) corresponded and (قاتل) fought.
شاركت أختي في بيت صغير.
“I shared a small house with my sister.”
Form IV (أفعَلَ/ يُفعِلُ) usually makes an intransitive verb transitive and a transitive verb doubly transitive, e.g. (أعلم) informed; (ألبس) dressed and (أرسل) sent.
ألبست الأم ابنتها الفستان الجديد.
“The mother dressed her daughter the new dress.”
Form V (تفعَّلَ/ يتفعَّلُ) is a reflexive of form II verbs, e.g. (تعلّم) learned; (تذكّر) remembered.
ما تذكّرت الموعد لكن صديقي ذكّرني به.
“I did not remember the appointment, but my friend reminded me.”