important; significant; crucial
Describes something that matters greatly, has serious consequences, or should not be neglected.
Health is more important than anything else.
この書類はとても大切だから、なくさないでください。
This document is very important, so please don't lose it.
Used for people, memories, or things that are emotionally valued and irreplaceable.
家族は私にとって一番大切な存在です。
My family is the most precious thing to me.
これは祖母からもらった大切な指輪です。
This is a precious ring I received from my grandmother.
careful; with care
Almost always used adverbially as 大切に, meaning to handle something with care or to treat it as important.
See also: 大切に
この本を大切に扱ってください。
Please handle this book with care.
彼は妻をとても大切にしている。
He treats his wife with great care.
He treasures his family very much.
I take good care of the watch my grandmother gave me.
Maintaining good health is important.
This is a precious memory to me.
大切 is a warmer, more common word for 'important/precious', while 肝要 is more formal and used to stress strict necessity.
Kana spelling is common in everyday writing, especially for emphasis or when avoiding kanji.