definition of av
Freebase(0.00 / 0 votes)Rate this definition: Av. Av is the eleventh month of the civil year and the fifth month of the ecclesiastical year on the Hebrew calendar. The name is Babylonian in origin and appeared in the Talmud around the 3rd century. This is the only month which is not named in the Bible. It is a summer month of 30 days. Av usually occurs in JulyâAugust on the Gregorian calendar.