必要(ひつよう)

必要(ひつよう) functions as both a na-adjective and a noun meaning 'necessary' or 'necessity.'

GRAMMATICAL PATTERNS:

• [noun]が必要(ひつよう)だ: [noun] is necessary
• 必要(ひつよう)な[noun]: necessary [noun]
• 必要(ひつよう)がある: there is a need (to)
• 必要(ひつよう)はない: there is no need (to)
• 必要(ひつよう)に応(おう)じて: as needed, according to necessity

COMMON EXPRESSIONS:

• 必要(ひつよう)書類(しょるい): required documents
• 必要(ひつよう)最低限(さいていげん): bare minimum necessity
• 必要(ひつよう)経費(けいひ): necessary expenses

OPPOSITE:
不必要(ふひつよう) (unnecessary)

NOTE:
When expressing personal need, the pattern XがYに必要(ひつよう)だ (X is necessary for Y) is common. For 'I need X,' Japanese often uses Xが要(い)る or Xが欲(ほ)しい instead.