skeptic
n.n. someone who is doubtful about something and does not believe it until they see proof. You use this to describe a person who questions new ideas or facts.
n. a person who questions the validity of a claim or the reliability of a source. Often used to describe individuals who maintain a critical attitude toward new information or established beliefs.
The scientist remained a skeptic until the results were published.
Many people were skeptics about the new technology until they saw it work in real life.
While the initial report was met with enthusiasm, a growing number of skeptics pointed out the lack of peer-reviewed evidence to support the claims of the researchers.
Borrowed from Middle French sceptique (but with a pronunciation closer to that of the Greek etymon), or possibly directly from Late Latin scepticus (originally attested only in the plural Scepticī (“the sect of Skeptics”)), from Ancient Greek σκεπτικός (skeptikós, “thoughtful, inquiring”), from σκέπτομαι (sképtomai, “I consider”), compare to σκοπέω (skopéō, “I view, examine”).