sure ‧ ly S1 W2 /ˈʃɔːli $ ˈʃʊrli/ BrE AmE adverb
1 . [sentence adverb] used to show that you think something must be true, especially when people seem to be disagreeing with you:
You must have heard about the riots, surely?
There must surely be some explanation.
Surely we can’t just stand back and let this happen?
2 . surely not spoken used to show you cannot believe that something is true:
‘The chairman’s just handed in his resignation.’ ‘Surely not.’
3 . formal certainly:
Such sinners will surely be punished.
4 . American English old-fashioned used to say ‘yes’ to someone or to express agreement with them
⇨ slowly but surely at ↑ slowly (2)