Synonyms for certainly

Adverb

1. surely, certainly, sure, for sure, for certain, sure enough, sure as shooting,certain(predicate) (vs. uncertain)

usage: definitely or positively (`sure' is sometimes used informally for `surely'); "the results are surely encouraging"; "she certainly is a hard worker"; "it's going to be a good day for sure"; "they are coming, for certain"; "they thought he had been killed sure enough"; "he'll win sure as shooting"; "they sure smell good"; "sure he'll come"