The simple passive stem has a prefixed nun (נ). It is built from the ground form נַקְטַל. Note that when the קָ and קְ of the Qal perfect inflection are exchanged for נִקְ, the Niph’al perfect is formed

The intensive active stem doubles the middle radical. If the middle radical is doubled and the קָ and קְ of the Qal are changed to קִ, the Pi’el perfect is formed. There is one exception. The vowel ( ֵ  ) of the 3ms ֵקִטֵּל.

The intensive passive stem doubles the middle radical. When the middle radical is doubled and the קָ or קְ of the Qal perfect is changed to קֻ, the Pu’al perfect is formed (קָטַּל).

The intensive reflexive stem doubles the middle radical and prefixes הִתְ. The Hithpa’el perfect is formed by the doubling of the middle radical, substituting קַ for קָ ,קְ and adding the prefix הִתְ to the Qal perfect form. The third masculine singular form is an exemption.

The causative stem has a prefixed ה. The ground form is הַקְטַל, which becomes הִקְטִיל in the third masculine singular. Before the vowel additions (ָ ה, and וּ) the ִי is retained and accented (הִקְטִ֣ילָה). Before the addition of consonants, the pathah ( ַ  ) is retained. The Hiph’il perfect may be formed by changing the קָ, קְ of the Qal perfect to הִקְ, and inserting ִי in the third masculine singular, third feminine singular, and third common plural. The vowels of the third feminine singular and third common plural were originally i-a in the perfect and a-i in the imperfect.

The causative passive had the prefixed ה with the vowel  ָ   (ŏ). Sometimes, the original  ֻ   takes place. Note the change of the קָ ,קְ of the Qal perfect to הָקְ to form the Hoph’al perfect.