All Arabic verbs have a root of 3 or 4 letters. To make different verbs, suffixes and prefixes are added or certain letters are dropped. 

The verb ‘فعل’ (to do)  is commonly a template to demonstrate how verbs change so not all the forms demonstrated have a meaning. Using the same verb across the different verb forms makes it easy to understand what has been added to the root, or what is missing from the root.

 

 

 

 

مُجرّد ثُلاثِيّ
Tripartite Bare [Verb]

No extra letter has been added to the 3 root letters
ف ع ل

Form I

فَعَلَ، يفْعُلُ
فَعَلَ، يفْعِلُ
فَعَلَ، يفْعَلُ
فَعُلَ، يفْعُلُ
فَعِلَ، يفْعَلُ
فَعِلَ، يفْعِلُ

 

مزيد ثُلاثِيّ
Tripartite Affixed [Verb]

A letter or letters have been added to the 3 root letters
ف ع ل

Forms II-XI

 

مُجرّد رُباعيّ
Quadripartite Bare [Verb]

No extra letter has been added to the 4 root letters.
ف ع ل ل

مزيد رُباعِيّ
Quadripartite Affixed [Verb]

A letter or letters have been added to the 3 root letters
ف ع ل ل

Forms II-IX