必要
1
necessary;needed;essential;indispensable
必用 can imply has to be used rather than is just needed
私達が生きていくためには衣食住が必要です。
We need food, clothes and a home in order to live.
2
necessity;need;requirement
歯医者に行く必要はないですよ。
You don't need to go to the dentist's.
Other forms
必用 【ひつよう】