postulation

[L. postulatio: cf. F. postulation.]
The act of postulating, or that which is postulated; assumption; solicitation; suit; cause.

noun

Something taken to be true without proof: assumption, postulate, premise, presupposition, supposition, theory, thesis. See reason/unreason.

The noun has 2 meanings:

Meaning #1: (logic) a declaration of something self-evident; something that can be assumed as the basis for argument
  Synonym: predication

Meaning #2: a formal message requesting something that is submitted to an authority
  Synonyms: request, petition