ا ج جʾ-j-j
(ض، ن) أَجَّتِ النَّارُ تَئِجُّajjati an-nār taʾijju / تَؤُجُّ أَجِيْجًاtaʾujju ajījan: (of fire) to blaze and for its flames to rise with a roar; أَجَّ الْمَاءُ يَؤُجُّ أُجُوْجًاajja al-māʾ yaʾujju ujūjan: (of water) to be salty and bitter.
أُجَاجujāj (pattern (wazn) فُعَالfuʿāl, adjective): water that is salty and bitter, unfit to drink; the opposite of عَذْبʿadhb (sweet). The lexicographers connect it to the blazing of fire, because such water burns the throat. This root occurs three times in the Quran, every time in this form: ﴿هٰذَا عَذْبٌ فُرَاتٌ وَّهٰذَا مِلْحٌ أُجَاجٌ﴾ (Al-Furqān 25:53)