Abjad

An abjad (/ˈæbdʒæd/,[1] Arabic: أبجد, Hebrew: אבגד), also abgad,[2][3] is a writing system in which only consonants are represented, leaving the vowel sounds to be inferred by the reader.

According to the formulations of Peter T. Daniels,[6] abjads differ from alphabets in that only consonants, not vowels, are represented among the basic graphemes.

Phoenician gave rise to a number of new writing systems, including the widely used Aramaic abjad and the Greek alphabet.

A "pure" abjad is exemplified (perhaps) by very early forms of ancient Phoenician, though at some point (at least by the 9th century BC) it and most of the contemporary Semitic abjads had begun to overload a few of the consonant symbols with a secondary function as vowel markers, called matres lectionis.

The phonetic structure of the Greek language created too many ambiguities when vowels went unrepresented, so the script was modified.

They did not need letters for the guttural sounds represented by aleph, he, heth or ayin, so these symbols were assigned vocalic values.

Similarly, the Brāhmī abugida of the Indian subcontinent developed around the 3rd century BC (from the Aramaic abjad, it has been hypothesized).

In most cases, the absence of full glyphs for vowels makes the common root clearer, allowing readers to guess the meaning of unfamiliar words from familiar roots (especially in conjunction with context clues) and improving word recognition[citation needed][dubious – discuss] while reading for practiced readers.