- Open to doubt or skepticism.
- Susceptible to being questioned or challenged.
- Of doubtful quality or authenticity.
From the latin word questionare meaning "to ask" or "to question".
- The validity of the research is questionable.
- The authenticity of the painting is questionable.
- The company's financial practices are questionable.
- His motives are questionable.
- The evidence presented in the trial was questionable.