根拠|こんきょkonkyo[1]atamadaka (head-high)

1. nounbasis; grounds; foundation; reason; authority
   その噂うわさは全まったく根拠こんきょがなかった。↗

   The rumor was completely without foundation.
2. nounbase (of operations)
3. noun, gobase (of a group of stones)

• Synonym理由りゆうNeutralA reason or cause, centered on explaining why something happened; 「根拠」 is the basis that backs up a claim or argument.
• Synonym裏付けうらづけNeutralBacking or corroboration for a claim, as in 「裏付けを取る」; the emphasis is on verifying facts, not on the grounds themselves.
• Synonym根底こんていWrittenThe root or foundation of a thing, as in 「根底から覆す」; written/formal prose.
• Synonym証あかしNeutralProof, or a token of one's feelings, as in 「愛の証」; carries a literary flavor.
• SynonymベースNeutralA loanword for a base or basis, as in 「ベースキャンプ」.
• Synonym基盤きばんWrittenThe foundation underpinning business, daily life and the like, as in 「生活基盤」; written/formal prose.
• Synonym証拠しょうこNeutralObjective evidence or proof, as in 「証拠不十分」; centers on establishing facts.
• Synonym土台どだいNeutralA physical foundation or base; also an adverb meaning fundamentally, as in 「どだい無理」.
• Synonym道理どうりNeutralReason or common sense, as in 「道理で」; stresses what is reasonable or natural.
• Synonym訳わけNeutralA reason or cause, common in colloquial speech, as in 「そういう訳で」.
• Synonym由よしWrittenWritten word for a reason, or for 'I hear that', as in 「元気な由」; has an epistolary flavor.
• Synonym拠り所よりどころNeutralSomething one relies on, emotionally or as grounds, as in 「心の拠り所」; stresses being an anchor or prop.
• Synonym証左しょうさWrittenWritten/formal word for evidence or corroboration, as in 「何よりの証左」.
• Synonym証跡しょうせきWrittenWritten term for evidence or traces, legal-technical in flavor; rarely used today.
• Synonym信証しんしょうWrittenWritten word for evidence, or a sign that vouches for something; rare today — everyday speech uses 「証拠」.
• Synonym明証めいしょうWrittenWritten word for clear, unmistakable proof; rarely used today.
• Related一理いちりNeutralSome measure of reason or truth, as in 「一理ある」; stresses that something is partly valid.
• Related立脚地りっきゃくちWrittenOne's standpoint or starting point for thinking; leans toward written/formal prose.
• Related立脚点りっきゃくてんWrittenA standpoint or viewpoint, synonymous with 「立脚地」; leans toward written/formal prose.
• Related徴証ちょうしょうWrittenWritten word for a sign or token; rarely used today.

Use 「根拠」 for the grounds backing a claim or judgment, as in 「根拠のない噂」. For a cause or reason use 「理由」 or the colloquial 「訳」; for evidence use 「証拠」; for corroborating support use 「裏付け」; for something to lean on emotionally use 「拠り所」; for partly valid points use 「一理」. The written words 「証左」「証跡」「信証」「明証」「徴証」 and 「由」 are rare or formal.

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

1. 物事ものごとを成り立なりたたせるもととなる理由りゆう。
2. ねじろ、本拠ほんきょ。