Writing system

In the 17th century Yoruba was written in the Ajami script^[10]. Modern Yoruba orthography originated in the early work of CMS missionaries working among the Aku in Freetown, notably Kilham and Raban. They assembled vocabularies and published short notes on Yoruba grammar. One of their informants in Sierra Leone was Crowther, who later would proceed to study his native language Yoruba. In early grammar primers and translations of portions of the English Bible, Crowther used the Latin alphabet largely without tone markings. The only diacritic used was a dot below certain vowels to signify their open variants [ɛ] and [ɔ], viz. ẹ and ọ. Over the years the orthography was revised to take care of tone marking among other things. In 1875 the Church Missionary Society (CMS) organised a conference on Yoruba Orthography; the standard devised there was the basis for the orthography of the steady flow of religious and educational literature over the next seventy years.

The current orthography of Yoruba derives from a 1966 report of the Yoruba Orthography Committee, along with Ayọ Bamgboṣe's 1965 Yoruba Orthography, a study of the earlier orthographies and an attempt to bring Yoruba orthography in line with actual speech as much as possible. Still largely similar to the older orthography, it employs the Latin alphabet modified by the use of the digraph gb and certain diacritics, including the traditional vertical line set under the letters E̩/e̩, O̩/o̩, and S̩/s̩. In many publications the line is replaced by a dot (Ẹ/ẹ, Ọ/ọ, Ṣ/ṣ). The vertical line has been used to avoid the mark being fully covered by an underline.

The Latin letters c, q, v, x, z are not used.

The pronunciation of the letters without diacritics corresponds more or less to their International Phonetic Alphabet equivalents, except for the labial-velar stops k͡p (written as <p>) and [ɡ͡b] (written as <gb>), in which both consonants are pronounced simultaneously rather than sequentially. The diacritic underneath vowels indicates an open vowel, pronounced with the root of the tongue retracted (so <ẹ> is pronounced [ɛ̙] and <ọ> as [ɔ̙]). <Ṣ> (or <s̩>) represents a postalveolar consonant [ʃ] like the English sh, <y> represents a palatal approximant like English y, and <j> a voiced palatal plosive, as is common in many African orthographies.

In addition to the vertical bars, three further diacritics are used on vowels and syllabic nasal consonants to indicate the language's tones: an acute accent (´) for the high tone, a grave accent (`) for the low tone, and an optional macron (¯) for the middle tone. These are used in addition to the line in <ẹ> and <ọ>. When more than one tone is used in one syllable, the vowel can either be written once for each tone (for example, *òó for a vowel [o]caron is used for the rising tone (so the previous example would be written ǒ) and a circumflex for a the falling tone. with tone rising from low to high) or, more rarely in current usage, combined into a single accent. In this case, a