Historically, "Aviv" meant the stage in the growth of grain when the seeds have reached full size and are filling with starch, but have not dried yet. During the plague of hail (Exodus 9:31), the barley was aviv and the flax was giv`ol.
Secondary Meanings to Aviv
The month in the Hebrew calendar when the barley has reached or passed this stage (Ex. 13:4; 23:15) is called the "month of the Aviv"; the seventh of the Jewish civil year, and the first of the Biblical ecclesiastical year. It begins about the time of the vernal equinox (21st March). Since the Babylonian captivity, it has been called Nisan (Neh. 2:1). On the sixteenth day of the month, harvest was begun by gathering a sheaf of barley, which was offered as a sacrifice to God (Lev. 23:4-11).
The "Holiday of Aviv" (Hebrew: חג האביב, Chag Ha'Aviv), is an additional name for Passover; the Jewish holiday is celebrated on 15–21(22) Nisan, near the beginning of spring.