Surely is used to show that you are very confident that something is true or will happen. It often adds emotion, like surprise or doubt, to a statement.
From 'sure' plus the adverb-forming suffix '-ly'. 'Sure' itself comes from Old French 'seur' and Latin 'securus' meaning 'safe, free from care'.
When people say “Surely you’re joking,” they’re not just asking; they’re pushing their own belief onto you. 'Surely' is a sneaky way to argue while pretending just to be surprised.
Complete word intelligence in one call. Free tier — 50 lookups/day.