The root of اِجْتَابَ is ج و ب. Here it conveys traversing a forest or stretch of land. The additional tāʾ of Form VIII does not change the number of original root consonants.
CategoryForm
Active perfectاِجْتَابَ
Active imperfectيَجْتَابُ
Verbal nounاِجْتِيَابٌ
Active participleمُجْتَابٌ
Imperativeاِجْتَبْ
Prohibitionلَا تَجْتَبْ
In اِجْتَبْ, the long medial vowel contracts. The infixed tāʾ remains while the hollow stem undergoes a separate weak-letter alteration.