Doubly Weak Verbs
Doubly weak verbs have two gutturals in their roots, usually in the first and third root positions. A guttural in the second root position is only noteworthy in the pi'el, pu'al, and hithpa'el, and these are dealt with in Chapter 34-37 in Volume 2.
Verbs with a guttural in the second root position and a guttural in the first or third root position are not considered to be doubly weak verbs. The guttural in the second root position bring about only slight modifications, none of which are unexpected, to the verb forms in a paradigm. However, verbs with a hey in the third root position and a guttural in the second root position are considered to be doubly weak verbs and are dealt with in Chapter 58 in this volume.
Doubly weak verbs are affected by one, or both, or neither of the anomalies already described for the different weak verbs or irregular verbs in Volume 2.With doubly weak verbs all three letters usually remain in the different paradigms, but sometimes only the letter in the second position remains.