What is the Arabic meaning of word Muslim?

The Arabic word "Muslim" (مسلم) literally means "one who submits (to God)". It comes from the verb "aslama" (أَسْلَمَ), which means "to submit, to surrender, to resign oneself".

In a religious context, a Muslim is someone who submits to the will of Allah (God) and follows the teachings of Islam. This includes believing in the oneness of God, the prophethood of Muhammad, and adhering to the Five Pillars of Islam.