1To decide, choose, or determine something from among options; to make up one's mind.
夕食は何にするか、まだ決めていない。
I haven't decided what to have for dinner yet.
旅行のホテルはもう決めた。
I've already decided on the hotel for the trip.
リーダーは話し合いでみんなが決めた。
The leader was decided by everyone through discussion.
一度決めたことは最後までやり通したい。
Once I've decided on something, I want to see it through to the end.
2To land the decisive blow or move that settles a match or contest.
逆転のホームランが試合を決めた。
A go-ahead home run decided the game.
延長戦の一点が勝負を決めた。
A single point in overtime decided the match.
3To persist in doing something and see it through without giving up.
どんなに辛くても、最後までやると決めている。
No matter how hard it is, I'm determined to go through with it to the end.
彼女は独学で資格を取ると決めて、実際にやり遂げた。
She resolved to get the qualification through self-study, and actually pulled it off.
4To routinely do something as a fixed habit; usually appears as 決めている.
朝食は必ずパンと決めている。
I've made it a rule to always have bread for breakfast.
週末はジムに行くと決めている。
I've made it a habit to go to the gym on weekends.
5To assume something is true without confirming it, often as 〜と決めてかかる.
彼は自分が正しいと決めてかかっている。
He's convinced he's right without even considering otherwise.
頭から無理だと決めてかからないほうがいい。
You shouldn't assume from the start that it's impossible.
6Colloquially, to dress up or style oneself sharply; often written as キメる.
デートのために髪も服もばっちりキメた。
I styled my hair and outfit perfectly for the date.
彼はいつもスーツをきっちりキメている。
He always dresses sharply in a suit.
7To successfully pull off a move, pose, or action, as in sports or dance.
体操選手が着地をぴたりと決めた。
The gymnast nailed the landing perfectly.
写真のためにみんなでポーズを決めた。
We all struck a pose for the photo.
彼はライブの最後に決めゼリフをキメて盛り上げた。
He nailed his signature line at the end of the live show and got the crowd going.
8In judo, sumo, and similar sports, to apply a joint lock or hold that immobilizes an opponent.
選手は相手の腕を極めて一本を取った。
The athlete locked his opponent's arm and won by ippon.
9Colloquially, to have a drink; as slang, can also refer to taking illegal drugs.
仕事終わりに軽く一杯決めて帰った。
I had a quick drink after work before heading home.
逮捕された男は事件当時キメていたと供述した。
The arrested man stated that he had been high on drugs at the time of the incident.