Doubt  —n. 1 uncertainty; undecided state of mind. 2 cynicism. 3 uncertain state. 4 lack of full proof or clear indication. —v. 1 feel uncertain or undecided about. 2 hesitate to believe. 3 call in question.  in doubt open to question. No doubt certainly; probably; admittedly. Without doubt (or a doubt) certainly. [latin dubito hesitate]