Sometimes translated as "infidel"

Another spelling would be (Kafir).

It's from the root verb (Kafara) which means two things in Arabic. It either means:
1- deny the blessing (usually of God), and in this sense it's opposite to the verb (Shakara) which means be thankful or grateful). In this sense the Kaffir is someone who dnies that blessings of God. Or it can also used to mean:

2- Unbelieve, which is usually the case in common use. The the use of the first meaning is quite common in the Quranic literature. In this case the Kaffir would be the "unbeliever".

"Kaffir" (spelled with tow Fs) is a term of disrespect used in South Africa for "a black person."

KAFIR (mostly spelled with one F) is an Arabic term, which originally meant "farmer." This usage would be considered archaic today.

In its current usage, KAFIR is a negative term meaning someone who is in denial. The denial is supposed to constitute a lack of faith or lack of faithfulness. Most commonly, it is used to mean someone who, by virtue of belief, statements, or outward behavior, is eggregiously outside the boundaries of the faith community, not just a heretic.

"Infidel" used to be the Christian disparaging term for non-Christians. It is now commonly used as a "translation" for the Arabic term KAFIR.

Fuad

He's an infidel & Atheist means he dosen't belive in mercy God.

also means:
unbeliever
disbeliever
indidel
atheist
miscreant

HTH

Kafara is the past tense of Yakfour. It literally means to "cover." Probably Kafara is the root for the English word "cover." It was adopted in the Quran to become later a religious word. So a Kafir is a person who covers his God. It is a fact that every human-being believes in God. Even those who deny Him must be denying what exists. Simply if the IDEA of a god did not exist then there would not be a need to deny it, and hence the Arabic word Kafara, to cover the existence of the God. This in a way attests to the foolishness of the Kafer.

The word KAFFIR/KAFIR is an ARABIC word owns its origan from the word"KUFR",which literally means "to refuse" so the literal meanings of KAFIR
are"A person who refuse to a phenomenon"
According to Islam KAFFIR means a person; who refuse to beleive in the
monoism of THE GOD(ALLAH),prophethood of
HAZRAT MUHAMMAD(P.B.U.H.),to the dooms day,and some more things .these are called basic beleives of islam,A KAFFIR
refuse to beleive them all or any of them.
with best regards
KAMRAN NADEEM