doubt

[dout] /daʊt/
verb (used with object)
1.
to be uncertain about; consider questionable or unlikely; hesitate to believe.
2.
to distrust.
3.
Archaic. to fear; be apprehensive about.
verb (used without object)
4.
to be uncertain about something; be undecided in opinion or belief.
noun
5.
a feeling of uncertainty about the truth, reality, or nature of something.
6.
distrust.
7.
a state of affairs such as to occasion uncertainty.
8.
Obsolete. fear; dread.
Idioms
9.
beyond the shadow of a doubt, with certainty; definitely.
Also, beyond a doubt, beyond doubt.
10.
in doubt, in a state of uncertainty or suspense:
His appointment to the position is still in doubt.
11.
no doubt,
  1. probably.
  2. certainly:
    There is no doubt an element of truth in what you say.
12.
without doubt, unquestionably; certainly.
Origin
1175-1225; (v.) Middle English douten < Anglo-French, Old French douter < Latin dubitāre to waver, hesitate, be uncertain (frequentative of OL dubāre), equivalent to dub- doubt + -it- frequentative suffix + -āre infinitive suffix; (noun) Middle English doute < Anglo-French, Old French, derivative of the v.
Related forms
doubtable, adjective
doubtably, adverb
doubter, noun
doubtingly, adverb
doubtingness, noun
nondoubtable, adjective
nondoubter, noun
nondoubting, adjective
nondoubtingly, adverb
overdoubt, verb (used with object)
predoubt, noun, verb
predoubter, noun
undoubtable, adjective
undoubting, adjective
Synonyms
1, 2. mistrust, suspect, question. 5. indecision, irresolution.
Usage note
Doubt and doubtful may be followed by a subordinate clause beginning with that, whether, or if: I doubt that (or whether or if) the story is true. It is doubtful that (or whether or if) the story is true. There is some doubt that (or whether or if) the story is true. In negative or interrogative sentences, that almost always introduces the subordinate clause: I do not doubt that the story is true. Is it doubtful that the story is true? Is there any doubt that the story is true?
The expressions doubt but and doubt but that occur in all varieties of standard speech and writing: I don't doubt but she is sincere. There is no doubt but that the charges will affect his career. Doubt but what occurs mainly in informal speech and writing: There is no doubt but what the rainy weather will hurt the crops.
British Dictionary definitions for beyond a doubt

doubt

/daʊt/
noun
1.
uncertainty about the truth, fact, or existence of something (esp in the phrases in doubt, without doubt, beyond a shadow of doubt, etc)
2.
(often pl) lack of belief in or conviction about something: all his doubts about the project disappeared
3.
an unresolved difficulty, point, etc
4.
(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.
(obsolete) fear
6.
give someone the benefit of the doubt, to presume someone suspected of guilt to be innocent; judge leniently
7.
no doubt, almost certainly
verb
8.
(transitive; may take a clause as object) to be inclined to disbelieve: I doubt we are late
9.
(transitive) to distrust or be suspicious of: he doubted their motives
10.
(intransitive) to feel uncertainty or be undecided
11.
(transitive; may take a clause as object) (Scot) to be inclined to believe
12.
(transitive) (archaic) to fear
13.
(Irish) I wouldn't doubt someone, I would expect nothing else from someone
Derived Forms
doubtable, adjective
doubtably, adverb
doubter, noun
doubtingly, adverb
Usage note
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
Word Origin
C13: from Old French douter, from Latin dubitāre
Word Origin and History for beyond a doubt

doubt

v.

early 13c., "to dread, fear," from Old French doter "doubt, be doubtful; be afraid," from Latin dubitare "to doubt, question, hesitate, waver in opinion" (related to dubius "uncertain;" see dubious), originally "to have to choose between two things."

The sense of "fear" developed in Old French and was passed on to English. Meaning "to be uncertain" is attested in English from c.1300. The -b- was restored 14c. by scribes in imitation of Latin. Replaced Old English tweogan (noun twynung), from tweon "two," on notion of "of two minds" or the choice of two implied in Latin dubitare (cf. German Zweifel "doubt," from zwei "two").

n.

early 13c., from Old French dote (11c.) "fear, dread; doubt," from doter (see doubt (v.)).

Idioms and Phrases with beyond a doubt

beyond a doubt

Also,
beyond the shadow of a doubt
. Certainly so, undoubtedly so, as in
Beyond a doubt this is the best view of the valley
. This phrase, along with the earlier
without doubt
(dating from c. 1300), asserts the truth of some statement. W.S. Gilbert's version, in
The Gondoliers
(1889), is: “Of that there is no manner of doubt—no probable, possible shadow of doubt—no possible doubt whatever.” In this context
shadow
means “a trace or slight suggestion.” Another variant is
beyond a reasonable doubt
. This phrase is often used in court when the judge instructs the jury that they must be convinced of the accused's guilt or innocence beyond a reasonable doubt;
reasonable
here means “logical and rational.” Also see

doubt

see:
Encyclopedia Article for beyond a doubt

doubt

in Cartesian philosophy, a way of searching for certainty by systematically though tentatively doubting everything. First, all statements are classified according to type and source of knowledge-e.g., knowledge from tradition, empirical knowledge, and mathematical knowledge. Then, examples from each class are examined. If a way can be found to doubt the truth of any statement, then all other statements of that type are also set aside as dubitable. The doubt is methodic because it assures systematic completeness, but also because no claim is made that all-or even that any-statements in a dubitable class are really false or that one must or can distrust them in an ordinary sense. The method is to set aside as conceivably false all statements and types of knowledge that are not indubitably true. The hope is that, by eliminating all statements and types of knowledge the truth of which can be doubted in any way, one will find some indubitable certainties.

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