Kafir (Arabic: كافر kāfir; plural كفّار kuffār; feminine كافرة kāfirah) is an Arabic term (from the root K-F-R "to cover") meaning "unbeliever", or "disbeliever". The term alludes to a person who rejects or disbelieves in God and the teachings of the Islamic Prophet Muhammad, and denies the dominion and authority of God; or otherwise does not heed the beliefs and prescriptions held by the religion of Islam. It is used as a derogatory term. Unbelief is called kufr. Kafir is sometimes used interchangeably with mushrik (مشرك, those who commit polytheism), another type of religious wrongdoer mentioned frequently in the Quran and Islamic works. The practice of declaring another self-professed Muslim a kafir is known as takfir.
The word kāfir is the active participle of the root K-F-R. As a pre-Islamic term it described farmers burying seeds in the ground. One of its applications in the Quran is also the same meaning as farmer. Since farmers cover the seeds with soil while planting, the word kāfir implies a person who hides or covers. Ideologically, it implies a person who hides or covers the truth. Poets personify the darkness of night as kâfir, perhaps as a survival of pre-Islamic religious or mythological usage. The noun for disbelief, "blasphemy", "impiety" rather than the person who disbelieves, is kufr.
The Hebrew words "kipper" and "kofer" share the same root as "kafir" כִּפֵּר, or K-F-R. "Kipper" has many meanings including, to "deny", "atone for", "cover", "purge", "represent", or "transfer". The last two meanings involve "kofer" that mean "ransom". "Kipper" and "kofer" are mostly likely used together in the Jewish faith to indicate God's transfer of guilt from innocent parties using guilty parties as "ransom".