na-adjective, noun
certain; sure; reliable; definite
Describes something that is firmly established, dependable, or without doubt. Used for facts, information, methods, and people. Often appears as 確実な or 確実に.
彼が来るのは確実だ。
It is certain that he will come.
Please convey only reliable information.
この方法なら確実に成功する。
With this method, you will definitely succeed.