Synonyms of surely in English:

surely


See definition of surely

adverb

1‘surely you remembered to pack a toothbrush?’

SYNONYMS
it must be the case that, I believe that, assuredly, without question
informal don't tell me that … not …

2‘give me some water, or I shall surely die’

SYNONYMS
certainly, for certain, for sure, to be sure, definitely, undoubtedly, without doubt, doubtless, beyond any shadow of a doubt, beyond the shadow of a doubt, indubitably, unquestionably, incontestably, irrefutably, incontrovertibly, undeniably, without fail, inevitably, unavoidably
informal sure

3‘their real achievement lay in slowly but surely creating and manipulating public opinion’

SYNONYMS
firmly, steadily, confidently, solidly, securely, unhesitatingly, unfalteringly, unswervingly, determinedly, doggedly, assuredly