wafer

noun

1. A light, thin, flat biscuit/cookie.

   “I was at the Mathematical School, where the Maſter taught his Pupils after a Method ſcarce imaginable to us in Europe. The Propoſition and Demonſtration were fairly written on a thin Wafer, with Ink compoſed of a Cephalick Tincture. This the Student was to ſwallow upon a faſting Stomach, and for three days following eat nothing but Bread and Water. As the Wafer digeſted, the Tincture mounted to his Brain, bearing the Propoſition along with it.”

2. A thin disk of consecrated unleavened bread used in communion.
3. A soft disk originally made of flour, and later of gelatin or a similar substance, used to seal letters, attach papers etc.

   “The house supplied him with a wafer for his present purpose, with which, having sealed his letter, he returned hastily towards the brook side, in order to search for the things which he had there lost.”

4. A thin disk of silicon or other semiconductor on which an electronic circuit is produced.

verb

1. (transitive)To seal or fasten with a wafer.

   “[M]y Father, who knew he was well, wafered the paragraph upon a sheet of paper, and sent to his Lodgings.”

   “[T]he beginning of de Barral's end became manifest to the public in the shape of a half-sheet of note-paper wafered by the four corners on the closed door […].”