ن ض خn-ḍ-kh
(ف) نَضَخَ يَنْضَخُ نَضْخًاnaḍakha yanḍakhu naḍkhan: (of a spring) to gush forcefully and throw up spray. (This verb is not used in the Quran.)
نَضَّاخَةٌnaḍḍākhah (intensive form, ṣīghat al-mubālaghah, on the pattern of فَعَّالَةٌfaʿʿālah): (a spring) gushing abundantly; the lexicographers distinguish between نَضْحnaḍḥ and نَضْخnaḍkh in that نَضْخnaḍkh is more forceful. Only once in the Quran: ﴿فِيْهِمَا عَيْنٰنِ نَضَّاخَتٰنِ﴾ (Ar-Raḥmān 55:66)