Abjad

An abjad (pronounced /ˈæbdʒɑːd/ or /ˈæbdʒæd/) is a type of writing system where each symbol or glyph stands for a consonant, leaving the reader to supply the appropriate vowel. So-called impure abjads do represent vowels, either with optional diacritics, a limited number of distinct vowel glyphs, or both. The name abjad is based on the old Arabic alphabet's first four letters—a, b, j, d—to replace the common terms "consonantary" or "consonantal alphabet" to refer to the family of scripts called West Semitic.