Quadruple VS
Synonym Boundary: "理由", "理性", "いわく", "国家理性"
All represent the core concept "reason", but require precise selection.
Japanese Option A
理由
りゆう (riyū)
N4 / CEFR
Japanese Option B
理性
りせい (risei)
N3 / CEFR
Japanese Option C
いわく
いわく (iwaku)
N2 / CEFR
Japanese Option D
国家理性
こっかりせい (kokkarisei)
C2 / CEFR
Quadruple VS Nuance Contrast & Social Differences
When expressing "reason" in Japanese, you must carefully distinguish between "理由", "理性", "いわく", "国家理性" based on context.
- 理由 (りゆう (riyū) - Level: N4): Maps to "reason, motive" and is used when A noun referring to the cause or explanation for something. Often used with なぜ.
- 理性 (りせい (risei) - Level: N3): Maps to "reason; intellect; self-control; sanity; rational mind" and is used when Refers to reason, intellect, self-control, sanity, or the rational mind that suppresses emotional impulses to make logical and moral decisions. Often used as 理性を失う.
- いわく (いわく (iwaku) - Level: N2): Maps to "reason, cause, history, legend (often with a negative connotation or mystery)" and is used when Often used to introduce something mysterious, suspicious, or with a specific backstory. Can also mean 'according to...' when quoting someone, often with skepticism..
- 国家理性 (こっかりせい (kokkarisei) - Level: C2): Maps to "reason of state / raison d'état" and is used when Essential structural term in CEFR C2 vocabulary syllabus..
Context for "理由"
遅刻した理由を教えてください。
Please tell me the reason for being late.
Context for "理性"
激しい怒りを感じたとしても、感情のままに行動せず、_______を保って冷静に対処することが求められます。
Even if one feels intense anger, they are required to maintain reason and handle it calmly without acting on emotion.
Context for "いわく"
その屋敷にはいわくがあると言われている。
It is said that there is a story/mystery behind that mansion.
Context for "国家理性"
私は国家理性に興味があります。
I am interested in reason of state / raison d'état.
Synonym Mastery Challenge
Which Japanese word perfectly fits this blank space?
Fill in the blank: "遅刻した ＿＿＿ を教えてください。" (Meaning: "Please tell me the reason for being late.")
🎉 Correct Answer!
Remember: "理由" is correct here because it represents "reason, motive" in the context: "Please tell me the reason for being late.".