Skepticism is the doubting itself — the habit of not believing too fast, or, in philosophy, the idea that we cannot be sure we know. “Healthy skepticism” is praise in school and in science: do not believe every headline. In the news, “public skepticism” means many people do not trust a plan or a finding. This k-spelling is American; British English writes scepticism. It is a noun, a little more formal than “they doubt it,” so it shows up in essays, reports, and speeches more than in chat. Though actually, people do not always keep the school-of-thought meaning and the everyday feeling apart. If someone praises your skepticism, they mean you are not easily fooled. If they complain about your skepticism, they may only mean you are being difficult. The same noun wears both coats.