Derived verb forms

From one root, Arabic builds verbs with regular patterns: علم (to know), علّم (to teach), تعلّم (to learn), استعلم (to inquire). Each pattern adds a shade of meaning: making someone do it, doing it to oneself, asking for it.

Forms starting with an alif in the past, انفعل, افتعل, استفعل, begin with a connecting alif, written with no hamza: انتظر, اجتمع, استخدم. Form IV is the exception: أفعل, with a hamza: أرسل, أكمل.

Their verbal nouns follow patterns too: تعليم, انتظار, استخدام, إرسال. Only form IV's verbal noun takes a hamza below: إرسال.