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misdoubt (v.)

disbelieve, doubt the reality [of]

AC III.vii.62	[Soldier to Antony] Do you misdoubt / This sword and these my wounds?
AW I.iii.120	[Countess to Steward] I could neither believe nor misdoubt
AW III.vii.1	[Helena to Widow] If you misdoubt me that I am not she