Definition of postulation in US English:

noun

• 1A suggestion or assumption of the existence, fact, or truth of something as a basis for reasoning, discussion, or belief.

  ‘discrepancies between empirical findings and theoretical postulations’

  mass noun ‘the postulation of the existence of a lost continent’

• 2(in ecclesiastical law) a nomination or election of someone to an ecclesiastical office subject to the sanction of a higher authority.