Being important or significant; something that is serious or requires attention.
明日の会議は大事だから、遅れないでください。
Tomorrow's meeting is important, so please don't be late.
健康は何より大事だ。
Health is more important than anything.
それは大事な決断だから、よく考えてください。
That's an important decision, so think it over carefully.
Something valuable or precious; an item or thing to be treasured or treated carefully.
この時計は祖父からの大事な宝物だ。
This watch is a precious treasure from my grandfather.
彼女にとってあの写真はとても大事だ。
That photograph is very precious to her.
A serious matter or major incident; a problem or crisis of significant concern.
現場で小さなトラブルが起きたが、大事には至らなかった。
A minor problem occurred at the site, but it did not develop into a serious incident.
その問題は大事になりかねないので、早めに対処しよう。
That issue could become serious, so let's deal with it quickly.
An old-fashioned/literary sense meaning a great undertaking or grand enterprise.
大事を成すには忍耐と努力が必要だ。
To accomplish great things requires patience and effort.
A regional (Tochigi) dialectal use meaning 'all right' or 'okay' (i.e., 'daijōbu').
（栃木）「けがはない？」／「大事だよ。」
(Tochigi) "Are you hurt?" / "I'm fine."