A sceptic is a person who does not simply accept a claim, especially a claim many people already treat as true. Show them a confident story — a miracle cream, a big promise, a “everyone knows” fact — and they want reasons, proof, the bit that does not fit. It is not the same as being rude, and it is not the same as a cynic: a cynic thinks people are mostly selfish; a sceptic thinks this claim may be wrong. You can be a sceptic about one thing only (a diet, a rumour) without being a sceptic about everything. In older philosophy, Sceptics were thinkers who held back from saying “this is certain.” The spelling sceptic is British; American English writes skeptic. Both start with a /sk/ sound, like sky, not a soft c. Though actually, everyday “I’m sceptical” is often only “I am not convinced yet,” which is milder than living as “a sceptic.”