To be uncertain as to a truth or fact; be undetermined or undecided; waver or fluctuate in opinion; hesitate.To be in fear; be afraid.To be uncertain as to the truth or fact of; hold in question; question; hesitate to believe: as, to doubt the truth of a story.To be expectant or apprehensive of; believe hesitatingly or indefinitely.To distrust; be uncertain with regard to; be distrustful of: as, to doubt one's ability to execute a task.To fear; be afraid of.To cause to fear; put in fear; appal; daunt.n. Uncertainty with regard to the truth of a given proposition or assertion; suspense of judgment arising from defect of evidence or of inclination; an unsettled state of opinion; indecision of belief.n. A matter of uncertainty; an undecided case or proposition; a ground of hesitation.n. A difficulty suggested or proposed for solution; an objection.n. Difficulty; danger.n. Hesitating apprehension; fear; dread.n. Synonyms Indecision, irresolution, suspense, hesitation, hesitancy, misgiving, distrust, mistrust.n. A redoubt.