Certainly

наречие конечно, естественно, непременно, несомненно, безусловно Например: He is certainly better today. — Ему, несомненно, лучше сегодня. May I visit him? Yes, certainly. — Можно его навестить? Да, конечно. Синоним(ы): of course, sure, no doubt

Большой англо-русский словарь

Certainly

adverb 1. in a manner that is certain; with certainty 2. it is certain that; assuredly

Merriam-Webster's Collegiate Dictionary