ASSALAM O ALAIKUM!
In Islam the word “Shaitan” has been derived from “Shatan” which literally means “Separate.” As this cursed creature is far from humanity as well as from virtues (nekia), hence it is Shaitan.
It is also said that it has been derived from “Shaat” which means “fire”. Shaitan, who was a Jinn, was created with fire. Hence it is Shaitan.
Though both the meanings are correct, but the former one is more correct & justified.
In Masnad-e-Ahmad, Hazrat Abu Zarr (r.a.) narrated a Hadees which is as follows:
Muhammad (sal allah ho alaihi wasallim said to me, “O Abu Zarr! Seek refuge of Allah from the demons who are from Man & Jinn.” I said, “Are demons from Man also?” He (sal allah ho alaihi wasallim) said, “Yes.”
Once Muhammad (sal allah ho alaihi wasallim) said to Abu Zarr (r.a.) “Woman, Donkey & Black dog destroy the Salah (Nimaz).” Abu Zarr said, “Why only black dog has been said.” Muhammad (sal allah ho alaihi wasallim) said, “Black dog signifies Shaitan.” (Sahih Muslim)
One should always bear in mind that one who dies on the weapon of Pagan (Qafir), he will be a martyr (shaheed), but one who dies on the weapon of Shaitan, will be cursed.
One, on whom, pagans dominate & kill him, will get the bounty of Allah, & one whom Shaitan dominates is ruined.
Any mistake, on my part, if found, may please be forgiven.