The definition of who an Arab is has several aspects:

Ethnic identity: someone who considers himself or herself to be an Arab (regardless of racial or ethnic origin) and is recognized as such by others.
Linguistic: someone whose first language is Arabic (including any of its varieties); this definition covers more than 200 million people.
Genealogical: someone who can trace his or her ancestry back to the original inhabitants of the Arabian Peninsula.
Political: someone who is a resident or citizen of a country where Arabic is an official or national language, or is a member of the Arab League or is part of the wider Arab world; this definition would cover more than 300 million people, but it is rather simplistic and rigid in that it excludes the entire Diaspora but includes indigenous or migrant minorities
The relative importance of these factors is estimated differently by different groups. Most people who consider themselves Arabs do so on the basis of the overlap of the political and linguistic definitions. However, some members of groups which fulfill both criteria reject the identity on the basis of the genealogical definition; Lebanese Maronites, for example, may reject the Arab label in favor of a narrower Phoenecian-Lebanese national identity. Groups which use a non-Arabic liturgical language - such as Copts in Egypt - are especially likely to be considered non-Arab. Not many people consider themselves Arab on the basis of the political definition without the linguistic one—thus, Kurds or Berbers do not usually identify themselves as Arab—but some do (for instance, some Berbers do consider themselves Arabs, and Kurds were in some historical circumstances seen as Arabs or Turks or Persians). In addition, a majority of the population of Qatar and the United Arab Emirates is made up of non-citizen non-Arab immigrants and so the political definition does not apply there either.

A hadith of questionable authenticity[1], related by Ibn Asakir in Târîkh Dimashq and attributed by its narrator Salmân b. `Abd Allah to Islam's prophet Muhammad, expresses a common sentiment in declaring that:

"Being an Arab is not because of your father or mother, but being an Arab is on account of your tongue. Whoever learns Arabic is an Arab."
According to Habib Hassan Touma (1996, p.xviii), "An 'Arab', in the modern sense of the word, is one who is a national of an Arab state, has command of the Arabic language, and possesses a fundamental knowledge of Arabian tradition, that is, of the manners, customs, and political and social systems of the culture."

On its formation in 1946, the Arab League defined an "Arab" as follows:

"An Arab is a person whose language is Arabic, who lives in an Arabic speaking country, who is in sympathy with the aspirations of the Arabic speaking peoples."
The genealogical definition was widely used in medieval times (Ibn Khaldun, for instance, does not use the word Arab to refer to "Arabized" peoples, but only to those of originally Arabian descent), but is usually no longer considered to be particularly significant.

Etymology | Traditional genealogy | History | Religions | Who is an Arab?