理 論(りろん)

りろん

noun

theory

1. theory; principle

A systematic set of ideas explaining phenomena, based on reasoning and evidence.

その理論(りろん)は実験(じっけん)で証明(しょうめい)された。

That theory was proven by experiment.

理論(りろん)と実践(じっせん)は違(ちが)う。

Theory and practice are different.

彼(かれ)の理論(りろん)は正(ただ)しいと思(おも)う。

I think his theory is correct.

理論(りろん) is a compound: 理(り) (reason/principle) + 論(ろん) (argument/discourse).

Types

経済(けいざい)理論(りろん) (economic theory)
相対性(そうたいせい)理論(りろん) (theory of relativity)
進化(しんか)理論(りろん) (evolutionary theory)

Common collocations

理論(りろん)を立(た)てる (to formulate a theory)
理論(りろん)に基(もと)づく (to be based on theory)
理論的(りろんてき)（な） (theoretical)
理論(りろん)武装(ぶそう) (theoretical preparation)

Similar words

理論(りろん) (theory - systematic explanation)
仮説(かせつ) (hypothesis - proposed explanation to be tested)
法則(ほうそく) (law - established principle)

Related Words

Synonym: 学説(がくせつ) (academic/scholarly)

Compare: 論理(ろんり) (logic (vs theory))

Compare: 仮説(かせつ) (hypothesis)

Compare: 法則(ほうそく) (law)

Compare: 実践(じっせん) (practice)

general

Added 2026.1.16 8:13 · Revised 2026.9.2 12:02

04500/04708_riron