Ajam in Arabic means non-Arab, or in particular non-Arabic-speaker. Some consider it a derogatory word. In the Middle East, it commonly refers to Persians, while in al-Andalus it referred to speakers of Romance languages - becoming "Aljamiado" in Spanish in reference to Arabic-script writing of those languages - and in West Africa, Ajami similarly refers to the writing of local languages such as Hausa and Fulani in the Arabic alphabet.

The Arabic family name "Ajami", well-known bearers of which include Fouad Ajami, normally indicates Persian descent.

A Persian folk etymology derives the word from the name of an ancient Persian king, Jamshid; this is linguistically improbable. In many books postdating the Arab conquest, for instance the Shahnameh of Ferdousi , the word is used to refer to Iranians and to the Persian language.