The first classification depends on the number of original root letters.
ExampleOriginal root lettersClass
نَصَرَ3Thulaathi
ضَرَبَ3Thulaathi
بَعْثَرَ4Rubaa'i
Thulaathi therefore means a form with three original root letters; Rubaa'i means one with four.
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Introduction to Verb Scales (Abwab): Trilateral & Quadrilateral
The first classification depends on the number of original root letters.
ExampleOriginal root lettersClass
نَصَرَ3Thulaathi
ضَرَبَ3Thulaathi
بَعْثَرَ4Rubaa'i
Thulaathi therefore means a form with three original root letters; Rubaa'i means one with four.