An adverb expressing strong certainty or high probability (almost surely; very likely).
あなたならきっと合格しますよ。
If it's you, I'm sure you'll pass.
明日は雨が降りそうだが、きっと午後には止むだろう。
It looks like rain tomorrow, but it will most likely stop in the afternoon.
彼は約束を守る人だから、きっと来るはずだ。
He's someone who keeps promises, so he'll almost certainly come.
Used often as キッと to indicate a stern, severe, or sharp manner (e.g., to stare or scold sharply).
先生はキッと黒板を指して注意した。
The teacher pointed at the blackboard sharply and warned us.
彼女はキッと彼を見返してから答えた。
She glared at him and then answered sharply.
Describes something being tight, rigid, or having no slack (a mimetic use indicating firmness).
ロープをきっと結んでおいてください。
Please tie the rope tightly.
ネジをきっと締めてから運搬すること。
Make sure to tighten the screws before transporting.
An archaic usage meaning suddenly or abruptly; rarely used in modern Japanese.
（文語的）きっと扉が開き、誰かが入ってきた。
(Literary) Suddenly the door opened and someone entered.