弟
私の弟は学生です。
My younger brother is a student.
A male sibling younger than oneself.
弟はサッカーが上手です。
My younger brother is good at soccer.
Used regardless of age difference when referring to one's own younger brother. In formal contexts, '弟' may be replaced with '末弟' (まってい) or '弟弟' (ていてい) for clarity.
Related Phrases
Pro Tip
Age Difference Matters
In Japanese culture, '弟' strictly refers to a younger brother. If you are the older sibling, use '兄' (ani) for your older brother and '弟' for your younger one. Mixing them up can cause confusion.
Gold Rule
Politeness in Referring to Others' Siblings
When talking about someone else's younger brother, always use the honorific '弟さん' (otōto-san) unless you are very close to the family.
Word Origin
From Old Japanese *woto2* (をと), via contraction. The kanji '弟' is also read as 'te' or 'dai' in on'yomi, but 'otōto' is the standard kun'yomi for this meaning.
Usage Notes
1. Do not use '弟' to refer to someone else's younger brother unless you are very close to the family. Use '弟さん' (otōto-san) for politeness. 2. In some dialects, 'おとうと' may be pronounced 'otōdo' or 'ototo'. 3. The word can also mean 'junior' in general contexts (e.g., '弟子' / deshi / disciple).