親友|しんゆうshin'yuu[0]heiban (flat)

1. nounclose friend; bosom friend; buddy; crony; chum
   トムとフランクは親友しんゆうだ。↗

   Tom and Frank are good friends.

• Synonym仲良しなかよしNeutralSomeone on very good terms with you; colloquial, often used of children or intimate relationships.
• SynonymベストフレンドNeutralLoanword meaning one's best friend; colloquial and common among young people.
• Synonym大親友だいしんゆうNeutralStresses an especially close, trusted friend; carries a colloquial, exaggerated tone.
• Related仲間なかまNeutralA companion in some shared activity, as in 「仕事仲間」; the friendship is not necessarily deep.
• Related相棒あいぼうNeutralA partner, as in 「仕事の相棒」; the emphasis is on the working partnership, not deep friendship.
• Related茶飲み友達ちゃのみともだちNeutralA longtime friend to relax and chat with over tea; also a spouse married in later life for companionship. The bond is more casual than 「親友」.
• Antonym敵てきNeutralAn enemy or foe, also written 「仇」; the opposite of a 「親友」.
• Antonym仇あだNeutralAlso used as a suffix for a rival, as in 「恋敵」; the opposite of 「親友」.

Use 「親友」 for a friend you are extremely close to. 「大親友」 adds colloquial emphasis; 「相棒」 is a partner and 「仲間」 a companion in some activity; 「敵」 is the opposite. 「ベストフレンド」 is a casual loanword for best friend.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 極きわめて親したしい友人ゆうじん。