Synonym: challenge, dispute, mistrust, question, suspect. Similar words: no doubt, without doubt, double, double up, double back, subtle, trouble, troubled. Meaning: [daʊt] 
n. 1. the state of being unsure of something 2. uncertainty about the truth or factuality of existence of something. v. 1. consider unlikely or have doubts about 2. lack confidence in or have doubts about.
n. 1. the state of being unsure of something 2. uncertainty about the truth or factuality of existence of something. v. 1. consider unlikely or have doubts about 2. lack confidence in or have doubts about. 
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(61) I have no doubt about their genuineness.
(62) I doubt I'll win, but you never know .
(63) This planted the seeds of doubt in my mind.
(64) There is not much doubt about his guilt.
(65) Do you doubt what I say?
(66) The success of the system is not in doubt.
(67) Some experts doubt the economic worth of the project.
(68) I doubt if that was what he wanted.
(69) There can be no doubt that he is guilty.
(70) The authenticity of the manuscript is beyond doubt.
(71) I doubt their enthusiasm will last.
(72) I for one have no doubt that he's lying.
(73) No doubt I had blundered again.
(74) 'Do you think England will win?'-'I doubt it.'
(75) If I feel any doubt(sentencedict.com), I ask.
(76) There was little doubt in my mind.
(77) Recent events throw doubt on the president's political future.
(78) No doubt you'll have your own ideas.
(79) There's no doubt coffee perks you up.
(80) That claim is increasingly open to doubt.
(81) His succession as headmaster was not in any doubt.
(82) Her guilt was established beyond reasonable doubt.
(83) Cardinal Meschia was without doubt a singular character.
(84) Doubt was gnawing away at her confidence.
(85) There is no reason whatsoever to doubt her story.
(86) Fresh evidence has thrown doubt on her story.
(87) I wouldn't doubt that he'd want to help.
(88) I have no reason to doubt his word .
(89) He was often touched by doubt .
(90) I doubt the sanity of such a plan.
More similar words: no doubt, without doubt, double, double up, double back, subtle, trouble, troubled, dour, do up, dough, hand out, hold out, in and out, weed out, stand out, send out, find out, washed out, spread out, tremendous.