Describes events, clothing, language, or behavior that is official, ceremonial, or follows strict conventions.
Tonight's party is formal, so I'll go in a suit.
ビジネスメールではフォーマルな表現を使うべきだ。
You should use formal expressions in business emails.
At formal occasions like weddings, you should be careful about manners.
Please come to the party in formal attire.
You should use polite language in formal business situations.