原 (げん, gen: “principle”) + 理 (り, ri: “theory”)
原理 (hiragana げんり, romaji genri)
- A fundamental truth that bases on.
- An eternal law that is common over lots of fact.
- (philosophy) A basic fact which explains why something exist.
- (physics) A basic scientific law which explains how a thing works, especially, that is quite primitive and have been found at very long ago; a principle.
- Arukimedesu no genri
- Archimedes' principle
Usage notes 
- (physics): Law is often used as a translation word for 法則, and effect for 効果.
- (a fundamental truth): 真理
- (an eternal law): 法則
- (philosophy): 本質
Coordinate terms 
原理 (traditional and simplified, Pinyin yuánlǐ)
Derived terms