1911 Encyclopædia Britannica/Wafer

WAFER, a thin flat cake or sheet of paste, usually circular in shape. The derivation of the word, which is the same as “waffle,” a batter-cake cooked in waffle-irons and served hot, is given under “Goffer,” which is adapted from the French form of the Teutonic original. As articles of stationery, wafers consist of thin brittle, adhesive disks, used for securing papers together, and for forming a basis for impressed official seals. They are made of a thin paste of very fine flour, baked between “wafer irons” over a charcoal fire till the thin stratum of paste becomes dry and brittle and the flour starch is partly transformed into glutinous adhesive dextrin. The cake is cut into round disks with suitable steel punches. Bright non-poisonous colouring matter is added to the paste for making coloured wafers. They are also made of gelatin. Wafers of dry paste are used in medical practice to enclose powders or other forms of drugs, thus rendering them easy to swallow.

In ecclesiastical usage the term “wafer” is applied to the thin circular disk of unleavened bread, stamped with a cross, the letters I.H.S. or the Agnus Dei, which is the form of the consecrated bread as used in the service of the Eucharist by the Roman Catholic Church.