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Also known as consonantal alphabet, consonantary, consonantal writing

An abjad (; or abgad ) is a writing system in which only consonants are represented by letter signs, leaving the vowels to be inferred by the reader (unless represented otherwise, such as by diacritics). This contrasts with alphabets that 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.