-니깐 is similar to the more common -니까, but it sounds slightly stronger. It is one of the verb conjugation forms. It expresses a reason or background for some action, state, or plan, like "because" or "given that...". -니까 is a connective ending more commonly used in the middle of a sentence than at the end. Wen used as a sentence ending, it usually further explains what was already mentioned. Here are the variations. * -니 => mentions a reason with weaker nuance. It also has a somewhat literary feel. * -니까 => probably the most commonly used one of the three. * -니까는 => 는 adds emphasis. -니까는 is commonly shortened to -니깐. Examples: - 내일은 비가 온다니 등산은 다음에 가자. - 내일은 비가 온다니까 등산은 다음에 가자. (most natural for this kind of a simple case). - 내일은 비가 온다니깐 등산은 다음에 가자. - 오늘 회의장 준비 다 마쳐야 해요. 내일 아침 9시에 시작하니까요. = We must get the conference hall all ready. (Since) it's set to start at 9 am tomorrow.