Collins English-English Dictionary

doubt [daυt]

1. 1. n uncertainty about the truth, fact, or existence of something (esp in the phrases in doubt, without doubt, beyond a shadow of doubt, etc)

2. 2. n [often plural] lack of belief in or conviction about something

   all his doubts about the project disappeared

3. 3. n an unresolved difficulty, point, etc

4. 4. n [philosophy] the methodical device, esp in the philosophy of Descartes, of identifying certain knowledge as the residue after rejecting any proposition which might, however improbably, be false

5. 5. n [obsolete] fear

6. 6. vt. [tr; may take a clause as object] to be inclined to disbelieve

   I doubt we are late

7. 7. vt. [tr] to distrust or be suspicious of

   he doubted their motives

8. 8. vi. [intr] to feel uncertainty or be undecided

9. 9. vt. [tr; may take a clause as object] [Scot] to be inclined to believe

10. 10. vt. [tr] [archaic] to fear

11. 11. vt. [Etymology] C13: from Old French douter, from Latin dubitare

12. 12. adv [Usage] Where a clause follows doubt in a positive sentence, it was formerly considered correct to use whether: (I doubt whether he will come ), but now if and that are also acceptable. In negative statements, doubt is followed by that: I do not doubt that he is telling the truth. In such sentences, but (I do not doubt but that he is telling the truth) is redundant