Mater lectionis

A mater lectionis ( , ; Latin for 'mother of reading', pl.matres lectionis ; original Hebrew: אֵם קְרִיאָה, romanized: ʾēm qərîʾāh) is any consonant letter that is used to indicate a vowel, primarily in the writing of Semitic languages such as Arabic, Hebrew and Syriac. The letters that do this in Hebrew are alephא, heה, vavו and yudי, with the latter two in particular being more often vowels than they are consonants. In Arabic, the matres lectionis (though they are much less often referred to thus) are ʾalifا, wāwو and yāʾي.

The original value of the matres lectionis corresponds closely to what are called in modern linguistics glides or semivowels.