根底・根柢|こんていkontei[0]heiban (flat)

1. nounroot; basis; foundation
   この議論ぎろんの根底こんていには、問題もんだいとしている規則きそくが言語げんごに存在そんざいするという仮説かせつがある。↗

   Basic to the argument is the assumption that the rules in question are present in the language.

• Synonym基礎きそNeutralNeutral noun for a foundation (「基礎を固める」); covers building foundations and basic knowledge for study, while 「根底」 points to the deepest root of thoughts and things.
• Synonym基盤きばんNeutralNeutral noun for a base or platform (「生活基盤」「経済基盤」); the emphasis is on what holds up the whole structure.
• Synonym根本こんぽんNeutralNeutral noun for the root or essence (「根本的な解決」); stresses the essential source of a matter.
• Synonym土台どだいNeutralNeutral noun for a foundation or base, also an adverb meaning 'fundamentally' (「土台無理だ」); 「根底」 is noun only.
• SynonymベースNeutralNeutral loanword for a base or groundwork (「ベースを作る」); common in colloquial speech.
• Synonym下地したじNeutralNeutral noun for groundwork or an undercoat (「化粧の下地」); also aptitude or basic grounding, senses 「根底」 lacks.
• Synonym基本きほんNeutralNeutral noun for the basics (「基本を学ぶ」); stresses elementary essentials, while 「根底」 points to the deepest layer.
• Synonym元もとNeutralColloquial word for an origin or cause (「失敗は成功のもと」); everyday in tone compared with 「根底」.
• Related礎いしずえWrittenWritten/formal prose word for a cornerstone (「国の礎を築く」); carries a solemn tone 「根底」 does not.
• Antonym表面ひょうめんNeutralNeutral noun for the surface or outward appearance; the direct opposite of 「根底」.

Use 「根底」 for the deepest root of thoughts and things (「根底から覆す」「考えの根底にある」). For building foundations or basic knowledge say 「基礎」, for a supporting platform 「基盤」, for the essential source 「根本」. 「土台」 also works as an adverb, and colloquial 「ベース」 fits everyday speech; 「表面」 is the opposite.

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

1. もと。根本こんぽん。