و wāw the twenty-sixth letter of the Arabic and thirtieth of the Persian alphabet, corresponds to व in Sanskrit. When used to denote a num- ber, according to the Arabs, it stands for six. In ephemerides it represents Friday and the sign Libra. This letter is sometimes a consonant; when it is one of the labial letters, having the sound of the English w or v. It is also one of the حرف علت ḥurūf-i-iﻌllat, or weak letters; when it may serve with the vowel ẓamm or fatʼḥa, conveyed by the preceding consonant, to denote the different sounds of o, ū, and au. As the و is homogenous with ẓamm, if the former is quiescent and immediately following the latter, the sound of ẓamm is only prolonged by it, and the result is a simple long vowel. This vowel may have the power of either o or ū: when it has that of the first, the و is termed majʼhūl (unknown, concealed); either, because it does not occur in the Arabic language, or because the sound of ẓamm is here obscured by an ad- mixture of that of fatʼḥa: it is, also, called واوفارسي and واوعجمي. And when it has the power of ū, it is termed maﻌrūf (known); from its occurring in Arabic and exhibiting the full sound of ẓamm. When the quiescent و follows a letter having the vowel fatʼḥa, the diphthong au is formed, and the و is then called واوساکن ماقبل مفتوح. After the vowel kasr it never occurs. In some cases و though written, is not pronounced. Thus (1) in the words دو Two, تو Thou, چو When, &c. the sounds are simply those of ẓamm without prolongation; as, in this line of Niz̤āmī, چوتوگرکسي باشد آنہم توٴي chu to gar kase bāshad, ān-ham tuʼī, where the first syllable is short. This is called واوبيان ضمه wāw-i-bayān-i-ẓamma. (2) After خ which has