How to say "foundation" in Japanese

• 基礎きそJLPT N2approx.Common
  no-adjectiveThe general word for a foundation, covering both the literal base of a building and the figurative basis of knowledge, skills or a system; the word you want for abstract foundations.
  その考かんがえが彼かれの理論りろんの基礎きそとなっている。↗

  The idea underlies his theory.
• 土台どだいJLPT N1approx.Common
  nounThe physical base or understructure that a building stands on, also used figuratively for the groundwork of a plan or undertaking; close to 基礎 but with a more concrete, physical image.
  この家いえは土台どだいがしっかりしている。↗

  This house has a solid foundation.
• 根拠こんきょJLPT N1approx.Common
  nounMeans grounds or basis in the sense of justification — the evidence or reasoning behind a claim or decision — so it is seldom the word you want for a physical or structural foundation.
  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.
• ファンデーションCommon
  nounThe loanword for cosmetic foundation, the makeup applied to the face; use it only for this beauty sense, never for structural, figurative or institutional foundations.
• 財団ざいだんCommon
  nounA foundation in the institutional sense — an organization established to promote or fund activities — and not a word for a building's foundation or an abstract basis.
  何百なんびゃくという人々ひとびとがゴリラ財団ざいだん研究所けんきゅうしょへ電話でんわや手紙てがみを下くださいました。↗

  Hundreds of people called or wrote to the Gorilla Foundation.

Use 基礎 or 土台 for structural or figurative underpinnings, 根拠 for grounds or justification, 「ファンデーション」 for the cosmetic, and 財団 for a foundation as an institution.

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

• 基礎きそfoundation
• 土台どだいfoundation
• 根拠こんきょbasis
• ファンデーションfoundation (makeup)
• 財団ざいだんfoundation (institution)
• 根幹こんかんfoundation
• 下地したじgroundwork
• 基盤きばんbase
• 基金ききんfund
• 根底こんていroot
• 基軸きじくbasis
• 創建そうけんestablishment
• 基本きほんbasics
• 創刊そうかんfoundation (of a newspaper, magazine, etc.)
• 基底きていbase
• 基部きぶbase
• 営団えいだんcorporation
• 屋台骨やたいぼねframework (of a building)
• 大本おおもとroot
• 基もといbasis
• 大本たいほんfoundation
• ファンデfoundation (makeup)
• 芯地しんじpadding
• 拠り所よりどころgrounds
• 創成そうせいcreation
• 憑拠ひょうきょbasis
• 大宗たいそうleading figure
• ベースメイクbase makeup
• 肇造ちょうぞうestablishment
• 基壇きだんplatform on which a structure is built
• 元もとbasis
• 根本こんぽんfoundation
• 命いのちmost important thing
• 幹みきbackbone
• 地盤じばんfoundation (building, etc.)
• 根っこねっこroot (of a problem, etc.)
• 足場あしばfoothold (e.g. in business)
• 底辺ていへんbase (e.g. of support)
• 素地そじgroundwork
• 屋台やたいframework (of a building)