Matres lectionis (singular form: mater lectionis) are an early manner of indicating vowels in the Hebrew alphabet. The consonant symbols Jod י, Waw ו and Aleph א were (mis)used to give a rough indication of the quality of the vowel: Jod י indicates i or e, Waw ו indicates o or u, Aleph א indicates a, or less frequently, a different vowel. At the end of a word, also He ה can be used to indicate that a vowel should be pronounced. In some verb forms, matres lectionis are used almost always. Examples:
|א||Aleph||mostly ā||פארן Pārān|
|ה||He||mostly ā||לאה Lē'ā|
|ו||Waw||ō or ū||יואל Jō'ēl|
|י||Jod||ī, ē or ǣ||דויד Dāwīd|
Later, it became clear that the system of matres lectionis did not suffice to indicate the vowel precisely enough. Punctuation systems were developed accordingly.
According to Sass (5), already in the Middle Kingdom there were some cases of matres lectionis, i. e. consonant graphemes which were used to transcribe vowels in foreign words, namely in Punic (Jensen 290, Naveh 62), Aramaic and Hebrew (he, waw, jod; sometimes even aleph; Naveh 62). Naveh (ibid.) notes that the earliest Aramaic and Hebrew documents already used matres lectionis. Some scholars argue that therefore the Greeks must have borrowed their alphabet from the Arameans. But the practice has older roots: the Semitic cuneiform alphabet of Ugarit (13th ct. BC) already has matres lectionis (Naveh 138).
Jensen, Hans. 1970. Sign Symbol and Script. London: George Allen and Unwin Ltd. Transl. of Die Schrift in Vergangenheit und Gegenwart. VEB Deutscher Verlag der Wissenschaften. 1958, as revised by the author.
Naveh, Joseph. 1979. Die Entstehung des Alphabets. Transl. of Origins of the Alphabet. Zürich und Köln. Benziger.
Sass, Benjamin. 1991. Studia Alphabetica. On the origin and early history of the Northwest Semitic, South Semitic and Greek alphabets. CH-Freiburg: Universitätsverlag Freiburg Schweiz. Göttingen: Vandenhoeck & Ruprecht.