The Commens Dictionary

Quote from ‘Logical Tracts. No. 2. On Existential Graphs, Euler's Diagrams, and Logical Algebra’

Let a heavy dot or dash be used in place of a noun which has been erased from a proposition. A blank form of proposition produced by such erasures as can be filled, each with a proper name, to make a proposition again, is called a rhema, or, relatively to the proposition of which it is conceived to be a part, the predicate of that proposition.