The Commens Dictionary
Quote from ‘Sketch of Dichotomic Mathematics’
A Postulate would be a proposition necessary as a premiss for a course of deductive reasoning and predicating a contingent character of the hypothetical subject of that course of reasoning; and any proposition of that description would be a Postulate.
‘Postulate’ (pub. 20.11.15-09:40). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from http://www.commens.org/dictionary/entry/quote-sketch-dichotomic-mathematics-5.