How to say "basis" in Japanese

• 基本きほんJLPT N3approx.Common
  no-adjectiveCovers 'basis' as the fundamentals or essentials of a subject or skill — the basic principles themselves. It is not the word for a basis in the sense of grounds or evidence.
  「これは・・・」「軍手ぐんてとスコップ。園芸えんげい部ぶ基本きほん道具どうぐのひとつだよ」↗

  "This is ..." "Working glove and trowel. One of a gardening club's basic tools."
• 根拠こんきょJLPT N1approx.Common
  nounThis is the word when 'basis' means grounds or justification — the evidence or reasoning behind a claim or argument. It does not refer to a foundation that something is built on.
  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.
• ベースJLPT N1approx.Common
  nounA loanword for 'base' or 'basis' — the base layer or ingredient something is built from, as with a dish's basic ingredient. Natural where English 'base' would also fit.
  キューバリブレはラム酒らむしゅをベースにしたカクテルです。↗

  A Cuba Libre is a cocktail with a rum base.
• 基礎きそJLPT N2approx.Common
  no-adjectiveCovers 'foundation' and 'basis': the underlying layer or groundwork of a skill, system, or structure. Choose it when 'basis' means what something rests or is built on, rather than grounds for a claim.
  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
  nounPrimarily the physical foundation or platform a structure stands on, also used figuratively for what supports something. For 'basis' as grounds or evidence it is seldom the word you want.
  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.

Choose 根拠 for a basis as grounds or evidence, 基本 for the basics of a subject, 基礎 for the foundation something rests on, and 「ベース」 or 土台 for the base something is built on.

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

• 基本きほんbasics
• 根拠こんきょbasis
• ベースbase
• 基礎きそfoundation
• 土台どだいfoundation
• 基軸きじくbasis
• 基盤きばんbase
• 根底こんていroot
• 根幹こんかんfoundation
• 本位ほんいstandard
• 基底きていbase
• 基準きじゅんstandard
• 基調きちょうbasic tone
• 大本おおもとroot
• 基もといbasis
• 憑拠ひょうきょbasis
• 原拠げんきょgrounds
• 大根おおねroot
• 元もとbasis
• 材料ざいりょうgrounds (for a decision, judgement, etc.)
• 根本こんぽんfoundation
• 底辺ていへんbase (e.g. of support)
• 母胎ぼたいparent body
• 根ねroot (of all evil, etc.)
• 母体ぼたいparent body
• 資しmaterial
• 開基かいきbase (topology)
• 立脚地りっきゃくちfooting
• 立脚点りっきゃくてんfooting