An abugida is a writing system between syllabic and alphabetic scripts. It has sequences of consonants and vowels that are written as a unit, each based on the consonant letter. Vowels must be written down as well, but they are secondary.
Syllables are built up of consonants, each of which has an inherent vowel.
Diacritic symbols are used to change or mute the inherent vowel, and separate vowel letters may be used when vowels occur at the beginning of a syllable or on their own.
This is different from a truly alphabetic script, in which the vowels and consonants have the same status, and an abjad, whose vowels are left out. Ethiopic and some languages found on the Indian subcontinent are examples of abugidas.
The name 'abugida' is derived from the first four letters of the Ge'ez (Ethiopic) alphasyllabary writing system.