linguistic:translation, stylistic:tone
Etymology

The name of Cairo is derived from the Arabic al-Qāhirah (القاهرة), meaning 'the Vanquisher' or 'the Conqueror', given by the Fatimid Caliph al-Mu'izz following the establishment of the city as the capital of the Fatimid dynasty. Its full, formal name was al-Qāhirah al-Mu'izziyyah (القاهرة المعزيّة), meaning 'the Vanquisher of al-Mu'izz'. It is also supposedly due to the fact that the planet Mars, known in Arabic by names such as an-Najm al-Qāhir (النجم القاهر, 'the Conquering Star'), was rising at the time of the city's founding.

Egyptians often refer to Cairo as Maṣr (IPA:; مَصر), the Egyptian Arabic name for Egypt itself, emphasizing the city's importance for the country.

There are a number of Coptic names for the city. Tikešrōmi (Coptic: Ϯⲕⲉϣⲣⲱⲙⲓ Late Coptic:) is attested in the 1211 text The Martyrdom of John of Phanijoit and is either a calque meaning 'man breaker' (Ϯ-, 'the', ⲕⲁϣ-, 'to break', and ⲣⲱⲙⲓ, 'man'), akin to Arabic al-Qāhirah, or a derivation from Arabic قَصْر الرُوم (qaṣr ar-rūm, "the Roman castle"), another name of Babylon Fortress in Old Cairo. The Arabic name is also calqued as ⲧⲡⲟⲗⲓⲥ ϯⲣⲉϥϭⲣⲟ, "the victor city" in the Coptic antiphonary.

The form Khairon (Coptic: ⲭⲁⲓⲣⲟⲛ) is attested in the modern Coptic text Ⲡⲓⲫⲓⲣⲓ ⲛ̀ⲧⲉ ϯⲁⲅⲓⲁ ⲙ̀ⲙⲏⲓ Ⲃⲉⲣⲏⲛⲁ (The Tale of Saint Verina). Lioui (Ⲗⲓⲟⲩⲓ Late Coptic:) or Elioui (Ⲉⲗⲓⲟⲩⲓ Late Coptic:) is another name which is descended from the Greek name of Heliopolis (Ήλιούπολις). Some argue that Mistram (Ⲙⲓⲥⲧⲣⲁⲙ Late Coptic:) or Nistram (Ⲛⲓⲥⲧⲣⲁⲙ Late Coptic:) is another Coptic name for Cairo, although others think that it is rather a name for the Abbasid province capital al-Askar. Ⲕⲁϩⲓⲣⲏ (Kahiree) is a popular modern rendering of an Arabic name (others being Ⲕⲁⲓⲣⲟⲛ and Ⲕⲁϩⲓⲣⲁ) which is modern folk etymology meaning 'land of sun'. Some argue that it was the name of an Egyptian settlement upon which Cairo was built, but it is rather doubtful as this name is not attested in any Hieroglyphic or Demotic source, although some researchers, like Paul Casanova, view it as a legitimate theory. Cairo is also referred to as Ⲭⲏⲙⲓ (Late Coptic:) or Ⲅⲩⲡⲧⲟⲥ (Late Coptic:), which means Egypt in Coptic, the same way it is referred to in Egyptian Arabic.

Sometimes the city is informally referred to as Cairo by people from Alexandria (IPA:; Egyptian Arabic: كايرو).