An abjad, also abgad, is a writing system in which only consonants are represented, leaving the vowel sounds to be inferred by the reader. This contrasts with alphabets, which provide graphemes for both consonants and vowels. The term was introduced in 1990 by Peter T. Daniels. Other terms for the same concept include partial phonemic script, segmentally linear defective phonographic script, consonantary, consonant writing, and consonantal alphabet.

Arabic is a Central Semitic language of the Afroasiatic language family spoken primarily in the Arab world. The ISO assigns language codes to 32 varieties of Arabic, including its standard form of Literary Arabic, known as Modern Standard Arabic, which is derived from Classical Arabic. This distinction exists primarily among Western linguists; Arabic speakers themselves generally do not distinguish between Modern Standard Arabic and Classical Arabic, but rather refer to both as al-ʿarabiyyatu l-fuṣḥā or simply al-fuṣḥā (اَلْفُصْحَىٰ).