一理|いちりichiri[2]nakadaka (mid-high)

1. noun(a) principle; (a) reason; (a) point; some truth
   彼女かのじょのいうことは一理いちりある。↗

   She's got a point.

• Synonym理由りゆうNeutralThe most general word for a reason or cause. 「一理」 instead concedes that a statement has some truth, typically in the pattern 「一理ある」.
• Synonym理屈りくつNeutralLogic or reasoning, sometimes strained, as in 「理屈をこねる」; it leans toward logical argument, while 「一理」 today appears mostly as 「一理ある」, meaning partly true.
• Synonym訳わけCasualColloquial word for a cause or meaning, as in 「訳を話す」; it points to the reason behind something, while 「一理」 judges that a statement holds some truth.
• Related根拠こんきょNeutralBasis or grounds, as in 「根拠のない噂」; it leans toward evidence backing a claim, while 「一理」 is mostly used as 「一理ある」 to grant some truth.
• Related由よしWrittenWritten, archaic term for a reason, also meaning 'I hear that…' as in 「〜の由」; 「一理」 has no such hearsay sense.
• Related事由じゆうWrittenWritten term for the reason behind a matter, common in legal and official writing like 「欠勤事由」; 「一理」 evaluates whether a statement is sound.
• RelatedいわれWrittenWritten word for a reason or cause, most often the origin or history behind something, as in 「名前の謂れ」; 「一理」 instead grants that a view has a point.
• Related原由げんゆWrittenRare written word for the root cause of something; 「一理」 speaks of the reasonableness of a claim, not its origin.
• Related所以ゆえんWrittenWritten word for the essential reason why something is so, as in 「人の人たる所以」; 「一理」 concedes only a measure of truth.
• Antonym無理むりNeutralAntonym: unreasonableness or impossibility, also the forced or strained; it stands opposite to 「一理」's having a point.

For a plain reason or cause use 「理由」 or, colloquially, 「訳」. To concede that what someone says has some truth, say 「一理」, as in 「君の言うことにも一理ある」. For the origin or history of a name or custom use 「謂れ」, and for something unreasonable or impossible use 「無理」.

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

1. 一ひとつの道理どうり。一応いちおう納得なっとくできる理由りゆう。