What is the origin of the word "al-'uluj" and its derivatives and meanings?

"Alij" (علوج) is the plural of "ilj" (علج). In the Arabic language, it is used to describe a strong, tough man. It can also refer to a man from among the foreign disbelievers. Perhaps its etymological origin stems from the meaning of hardness and toughness, or from the ability to "treat" (علاج), which implies defending and struggling.