The structure of the Arabic verb is typically shown in the basis or so-called ‘fafala’ form as a series of consonant ‘radicals’, usually three, hence the term ‘tri-radicals’, and with vowels in between, to wit: ‘Consonant + Vowel + Consonant + Vowel + Consonant’ (C1 + V + C2 + C2 + V + C3). The partial survey reported here indicates that about half of the Arabic verbs have these two corresponding forms. In Classical Arabic, the forms seem to have been constructed in a semantically systematic fashion, but in modern Arabic, the data are rather complex and variegated. The authors report some of the major trends they have found so far and suggest some ways to describe them.