The 1901 Jewish Encyclopedia
Sixth letter of the Hebrew alphabet. The name possibly means "nail" or "hook," and the shape of the letter in the Phenician alphabet bears some resemblance to a hook. "Waw" is a labial spirant, identical in sound with the English "w." When preceded by the labial vowel "u," it blends with it ("uw"), the result being a long u-sound; and when an a-vowel precedes it, the two form the diphthong "au," which in Hebrew has passed into "o." At the beginning of a word (a position it rarely has in Hebrew) "waw" retains its consonantal value, except when followed by פ, נ, מ, or a letter with simple "shewa." As the first letter of verb-stems it has been replaced in Hebrew almost everywhere by "yod." As a numeral (in the later period) "waw" has the value of 6.
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Singer, Isidore, Ph.D, Projector and Managing Editor. Entry for 'Vav'. 1901 The Jewish Encyclopedia. https://www.studylight.org/encyclopedias/eng/tje/v/vav.html. 1901.