A term appears, in the general algebra of logic of Peirce, as well as in the logical graphs of the same logician, as a symbol which does not definitely and separately show its object, or more clearly speaking, as a proposition in which blanks are left for some or all of its subjects; as ‘– is a man,’ ‘– loves –.’
http://www.commens.org/dictionary/entry/quote-definitions-baldwins-dictionary-r-12