"Unleavened" refers to food that has not been made with yeast or a similar ingredient that makes it rise and become fluffy. It describes a flat and denser type of food, like unleavened bread or unleavened crackers. Full definition
34:26, as are provisions for the Sabbath, feasts three times a year, the use of unleavened bread in sacrifices, and the offering of the first fruits to Yahweh. (religion-online.org)
The kingdom, the power, and the glory were hidden in the liberation of a band of slaves from Egypt and in the sacrifice of a lamb and the eating of unleavened bread. (firstthings.com)
However, by the end of the year, the church council forced Calvin to resign his position and leave Geneva because he wanted to force church members to sign his doctrinal statement and articles of church organization (which few people wanted to do), and because he refused to serve communion with unleavened bread on Easter Sunday. (redeeminggod.com)