An immediate or on-the-spot decision; making a prompt choice without delay.
会議で問題が出ると、社長は即決で対応策を指示した。
When an issue came up in the meeting, the president immediately instructed a course of action.
店頭のセールで即決して買ってしまった。
I made a snap decision at the store sale and bought it.
彼は物事を即決するタイプだ。
He is the type of person who decides things on the spot.
In law: a summary judgment — a decision made promptly without a full trial when appropriate.
裁判所は証拠不十分として即決を下した。
The court issued a summary judgment citing insufficient evidence.