certainly certainly /ˈsɝːtənli/

adverb

1. () Definitely or positively (sure' is sometimes used informally for surely')  ( for certain , sure as shooting , for sure , certainly , sure , sure enough , surely )
   definitely or positively (sure' is sometimes used informally for surely')
    The results are surely encouraging
   the results are surely encouraging
    She certainly is a hard worker
   she certainly is a hard worker
    It's going to be a good day for sure
   it's going to be a good day for sure
    They are coming, for certain
   they are coming, for certain
    They thought he had been killed sure enough
   they thought he had been killed sure enough
    He'll win sure as shooting
   he'll win sure as shooting
    They sure smell good
   they sure smell good
    Sure he'll come
   sure he'll come
   

interjection

1. () Affirmative answers or indications of agreement.  ( ay [Dialect] , aye [Dialect] , ya [Informal, South Africa] , certainly , sure [Informal] , yea [Informal] , yeah [Informal] , yes , uh-huh [Informal] , yah [Informal, UK] , yep [Informal] , yup [Informal] )
   Affirmative answers or indications of agreement.