The Collaborative International Dictionary of English v.0.48:
Doubt \Doubt\, v. t.
1. To question or hold questionable; to withhold assent to;
to hesitate to believe, or to be inclined not to believe;
to withhold confidence from; to distrust; as, I have heard
the story, but I doubt the truth of it.
To admire superior sense, and doubt their own!
I doubt not that however changed, you keep
So much of what is graceful. --Tennyson.
To doubt not but.
I do not doubt but I have been to blame. --Dryden.
We doubt not now
But every rub is smoothed on our way. --Shak.
Note: That is, we have no doubt to prevent us from believing,
etc. (or notwithstanding all that may be said to the
contrary) -- but having a preventive sense, after verbs
of "doubting" and "denying" that convey a notion of
hindrance. --E. A. Abbott.
2. To suspect; to fear; to be apprehensive of. [Obs.]
Edmond [was a] good man and doubted God. --R. of
I doubt some foul play. --Shak.
That I of doubted danger had no fear. --Spenser.
3. To fill with fear; to affright. [Obs.]
The virtues of the valiant Caratach
More doubt me than all Britain. --Beau. & Fl.