決める
きめる · kimeru · JLPT N4 · verb-ichidan
to decide (v.t.)
🔑 kimeru: the KEY MEmo RUles — once it is written, the matter is decided
決 joins water (氵) with 夬, to break open: a dam bursts and the water commits to one course, which is the sense of settling a matter. 決める is the transitive partner of 決まる (to be decided), so you decide something: 日にちを決める, to fix the date.