An abugida (ɑːbᵿˈɡiːdə,_ˈæb-, from Ge'ez: አቡጊዳ), sometimes known as alphasyllabary, neosyllabary or pseudo-alphabet, is a segmental writing system in which consonant–vowel sequences are written as units; each unit is based on a consonant letter, and vowel notation is secondary, like a diacritical mark. This contrasts with a full alphabet, in which vowels have status equal to consonants, and with an abjad, in which vowel marking is absent, partial, or optional – in less formal contexts, all three types of script may be termed "alphabets". The terms also contrast them with a syllabary, in which a single symbol denotes the combination of one consonant and one vowel.
Related concepts were introduced independently in 1948 by James Germain Février (using the term néosyllabisme) and David Diringer (using the term semisyllabary), then in 1959 by Fred Householder (introducing the term pseudo-alphabet). The Ethiopic term "abugida" was chosen as a designation for the concept in 1990 by Peter T. Daniels. In 1992, Faber suggested "segmentally coded syllabically linear phonographic script", and in 1992 Bright used the term alphasyllabary, and Gnanadesikan and Rimzhim, Katz, & Fowler have suggested aksara or āksharik.
Abugidas include the extensive Brahmic family of scripts of Tibet, South and Southeast Asia, Semitic Ethiopic scripts, and Canadian Aboriginal syllabics. As is the case for syllabaries, the units of the writing system may consist of the representations both of syllables and of consonants. For scripts of the Brahmic family, the term akshara is used for the units.
In several languages of Ethiopia and Eritrea, abugida traditionally meant letters of the Ethiopic or Ge‘ez script in which many of these languages are written. Ge'ez is one of several segmental writing systems in the world, others include Indic/Brahmic scripts and Canadian Aboriginal Syllabics. The word abugida is derived from the four letters, ä, bu, gi, and da, in much the same way that abecedary is derived from Latin letters a be ce de, abjad is derived from the Arabic a b j d, and alphabet is derived from the names of the two first letters in the Greek alphabet, alpha and beta.