Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
Parts of peace-offerings were so called, because they were waved by the priests (Ex. 29:24, 26, 27; Lev. 7:20-34, 8:27, 9:21, 10:14, 15, etc.), in token of a solemn special presentation to God. They then became the property of the priests. The first-fruits, a sheaf of barley, offered at the feast of Pentecost (Lev. 23:17-20), and wheat-bread, the first-fruits of the second harvest, offered at the Passover (23:10-14), were wave-offerings.