Islāmic concept that became a literary genre distinguished by its broad humanitarian concerns; it developed during the brilliant height of ʿAbbāsid culture in the 9th century and continued through the Muslim Middle Ages.

The original sense of the word was simply “norm of conduct,” or “custom,” derived in ancient Arabia from ancestors revered as models. As such practice was deemed praiseworthy in the medieval Muslim world, adab acquired a further connotation of good breeding, courtesy, and urbanity.

Parallel to and growing out of this expanded social meaning of adab there appeared an intellectual aspect. Adab became the knowledge of poetry, oratory, ancient Arab tribal history, rhetoric, grammar, philology, and non-Arab civilizations that qualified a man to be called well-bred, or adīb. Such men produced a vast and erudite adab literature, concerned with man and his achievements and written in a style rich in vocabulary and idiom, and usually expressive and flexible. They included such writers as the 9th-century essayist al-Jāḥiẓ of Basra and his 11th-century follower Abū Hayyān at-Tawḥīdī; the 9th-century Kūfan critic, philologist, and theologian Ibn Qutaybah; and the 11th-century poet al-Maʿarrī.

As the golden age of the ʿAbbāsids declined, however, the boundaries of adab narrowed into belles lettres: poetry, elegant prose, anecdotal writing (maqāmāt). In the modern Arab world adab merely signifies literature.