When someone is unreasonably distrustful, it means that they have a strong feeling of suspicion towards something or someone without any logical or rational explanation. Some synonyms for unreasonably distrustful include paranoid, suspicious, skeptical, guarded, wary, and doubtful. If someone is paranoid, they are excessively fearful and overly suspicious of their surroundings. A skeptical person is someone who is doubtful of the authenticity of things. If someone is guarded, they are cautious and careful in their approach towards others. Being wary means being cautious and ready to anticipate potential danger or harm. Lastly, doubtful people are uncertain and lack confidence in the credibility or truthfulness of something. These are just a few examples of synonyms for "unreasonably distrustful".