兄さん|にいさんniisan[1]atamadaka (head-high)

1. nounolder brother; elder brother
   兄にいさんはよくおなりだと思おもいますが。↗

   I hope your brother is better.
2. nounbrother (as older-brother figure in friendly and or work relationship)
3. nounyoung man; buddy; fella; laddieusu. vocative

• Synonym兄ちゃんにいちゃんCasualA pet name for one's older brother, also used for young lads; more casual and affectionate than 「兄さん」.
• Synonym兄貴あにきCasualOlder brother, but also the big brother of gangs or a trade; carries a hearty, street-tough flavor.
• Synonym兄あにNeutralThe plain word for one's own older brother, used when mentioning him to others; objective, not a form of address.
• Related兄者あにじゃWrittenOlder brother; an old-fashioned term heard mainly in period dramas.
• Related兄御あにごFormalA respectful term for someone else's older brother; old-fashioned and rarely used today.
• Related大兄たいけいWrittenA written honorific used in letters between men for a senior or elder, as in 「〇〇大兄」.
• Related兄いあにいCasualOlder brother or senior, also a dashing young man; Edo-period colloquial speech with a coarse flavor.
• Related兄様にいさまFormalA polite way to address one's older brother with an upper-class family feel; more courteous than 「兄さん」.
• Antonym弟さんおとうとさんNeutralThe polite term for another person's younger brother; the counterpart of an older brother.

To address your older brother or a young man warmly, use 「兄さん」, as in 「お兄さん」. Go more casual and affectionate with 「兄ちゃん」, streetwise with 「兄貴」, or polite with 「兄様」. When mentioning your own brother to others, use 「兄」. 「弟さん」 is the opposite, a younger brother.

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

1. 自分じぶんの兄あにや義兄ぎけい、兄弟子あにでしなどを親したしみを込こめて呼よぶ語ご。
2. 若わかい男性だんせいを親したしみを込こめて呼よぶ語ご。にいちゃん。