二号|にごうnigou

1. nounnumber two
2. nounmistress; concubine

• Synonym第二だいにNeutralMeans second, mostly used attributively as in 「第二次世界大戦」. Formal in register.
• SynonymセカンドNeutralLoanword for second; also used for second base and second gear. Colloquial in feel.
• Synonym妾めかけNeutralRefers directly to a kept woman or concubine; 「二号」 is a euphemistic slang term for this.
• Synonym二番目にばんめNeutralThe second item in an order or sequence. Unlike 「二号」, it never means a mistress — colloquial 「二号」 carries that hidden sense.
• Related二番にばんNeutralMeans second; can indicate rank or placement as in 「二番手」, or the second item in a general sequence. 「二号」 is mostly about numbering.
• Related二つ目ふたつめNeutralThe second one in a series; colloquial, used when counting things.
• Related二着にちゃくNeutralThe second finisher in a race or competition; used mostly for horse racing and running races.
• Antonym本妻ほんさいNeutralAntonym: one's legal wife; stands opposite 「二号」 in its kept-woman sense.

Use 「二号」 for number two in a numbering scheme; colloquially it is also a euphemism for a kept woman. For second in an order say 「二番目」 or, when counting things, 「二つ目」; in formal prose use 「第二」. A mistress is called 「妾」 outright.

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

1. 二に番目ばんめ。第だい二に。
2. めかけ。