Postulate, v. t. [imp. & p. p. Postulated; p. pr. & vb. n. Postulating.]
1. To beg, or assume without proof; as, to postulate conclusions.
2. To take without express consent; to assume. The Byzantine emperors appear to have . . . postulated a sort of paramount supremacy over this nation. W. Tooke.
3. To invite earnestly; to solicit. [Obs.] Bp. Burnet.
2 other Webster entries under this spelling
Postulate, n.
1. Something demanded or asserted; especially, a position or supposition assumed without proof, or one which is considered as self-evident; a truth to which assent may be demanded or challenged, without argument or evidence.
2. (Geom.)
The enunciation of a self-evident problem, in distinction from an axiom, which is the enunciation of a self-evident theorem. The distinction between a postulate and an axiom lies in this, -- that the latter is admitted to be self-evident, while the former may be agreed upon between two reasoners, and admitted by both, but not as proposition which it would be impossible to deny. Eng. Cyc.
Postulate, a.
Postulated. [Obs.] Hudibras.
Shades of meaning
Fernald has no entry of its own for postulate; he lists it under assume.
He lists it without comment; the entries above explain its neighbors.