Questionable/ˈkwestʃənəbl/ Definition 1 of 4Pro Tip 1/2Expressing Doubt Use 'questionable' when you're unsure about the truth or effectiveness of something. The healer's methods were questionable and unproven. Pro Tip 2/2Lacking Evidence Apply 'questionable' when something seems false or lacks evidence. The authenticity of the artifact is questionable.