定 plan

If you are going to be a king, you have to plan to TAKE the correct crown.

an informal plan ★★★★★
予 (beforehand) + 定 (plan) = 予定 (an informal plan)

an informal plan (like to meet your friends for a movie)

establish ★★★☆☆
設 (establish) + 定 (plan) = 設定 (establish)

to establish a regulation or rule - also it is often seen on the 'setup' or 'preferences' menus of software when you install it.

make a serious decision ★★★☆☆
決 (decide) + 定 (plan) = 決定 (make a serious decision)

to make a real serious decision； like, "I know I'm always saying I'm going to lose 1２ pounds but this time I really mean it."

definition ★★☆☆☆
定 (plan) + 義 (righteousness) = 定義 (definition)

a definition (hey! recursion!)