firmly; unerringly; without missing, slipping, etc.

undoubtedly, assuredly, or certainly

The results are surely encouraging.

(in emphatic utterances that are not necessarily sustained by fact) assuredly

Surely you are mistaken.

inevitably or without fail

Slowly but surely the end approached.

yes, indeed

Surely, I'll go with you!

adverb

doubtfully , questionably , uncertain

adverb

absolutely , admittedly , assuredly , beyond doubt , beyond shadow of doubt , certainly , clearly , come what may , conclusively , decidedly , definitely , distinctly , doubtlessly , evidently , explicitly , fixedly , for certain , for real , indeed , indubitably , inevitably , inexorably , infallibly , irrefutably , manifestly , nothing else but , plainly , positively , rain or shine , to be sure , undoubtedly , unequivocally , unerringly , unfailingly , unmistakably , unquestionably , unshakably , with certainty , without fail