土台|どだいdodai[0]heiban (flat)

1. nounfoundation; base; basis
   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.
2. adverbfrom the beginning; from the outset; by natureoften in negative contexts

• Synonym基礎きそNeutralMeans foundation, as in 「基礎工事」 and 「基礎知識」; used for both buildings and abstract matters, and is more formal than 「土台」.
• Synonym根底こんていWrittenWritten/formal prose; means the root or basis, as in 「根底から覆す」; leans toward the fundamentals of thought or theory.
• Synonym元もとNeutralMeans the root or origin, as in 「元を正す」; leans toward source, and does not specifically refer to a load-bearing part.
• Synonym根本こんぽんNeutralWhen written 「根本」 it is still read 「ねもと」; covers the base of trees or pillars and the root of problems; 「土台」 is the foundation bearing what is above.
• SynonymベースNeutralLoanword meaning base, standard or home base, as in 「ベースになる」; leans colloquial and toward business use.
• Synonym基本きほんNeutralMeans basics or fundamentals, as in 「基本を学ぶ」; leans toward knowledge and skills, and does not refer to a building's foundation.
• Synonym基盤きばんWrittenWritten/formal prose; means base or footing, as in 「生活基盤」 and 「経営基盤」; leans toward a supporting framework.
• Synonym下地したじNeutralMeans groundwork, undercoat or aptitude, as in 「下地がある」; leans toward a base laid down in advance.
• Synonym根っこねっこCasualColloquial; means root or root cause, as in 「問題の根っこ」; leans toward the figurative essence of things.
• Synonym礎いしずえWrittenWritten/formal prose; means cornerstone, as in 「国の礎」; leans toward people or things that figuratively lay a foundation.
• Synonym基底きていWrittenWritten/formal prose; means a base or the mathematical basis; leans toward technical terminology.
• Synonym基部きぶWrittenWritten/formal prose; means the base part, as in 「首の基部」; leans toward anatomy and structure.
• Synonym根ねNeutralMeans a plant's roots and also the root of a matter, as in 「根が深い」; leans toward the growing root.
• Synonym台座だいざNeutralMeans the pedestal of a Buddha statue or sculpture, as in 「銅像の台座」; leans toward a stand for placing things on.
• Synonym礎石そせきWrittenWritten/formal prose; means a foundation stone, as in 「礎石を置く」; spans building and figurative use.
• Synonym根元ねもとNeutralRefers to the base of plants or pillars, as in 「木の根元」; it points to the bottom position, while 「土台」 is the load-bearing foundation.
• Related根源こんげんWrittenWritten/formal prose; means root or origin, as in 「悪の根源」; leans toward cause.
• Related突っ張りつっぱりNeutralMeans a prop or strut used for support, and also a sumo pushing attack; leans toward temporary bracing.
• Related支柱しちゅうNeutralMeans a supporting pillar and figuratively an emotional mainstay; leans toward upright support.
• RelatedつっかいCasualColloquial; a stick or pole used to prop something up, such as a door; leans toward temporary supports.

Use 「土台」 for a building's foundation or the basis of something; as an adverb it also means fundamentally or from the start, as in 「土台無理だ」. For formal use pick 「基礎」, for a supporting framework 「基盤」, for a metaphorical cornerstone 「礎」. 「根元」 and 「根」 are physical bases or roots, 「根っこ」 the colloquial root of a problem, 「ベース」 the loanword for base. Props and stands like 「支柱」, 「台座」 and 「突っ張り」 hold things up rather than found something.

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

1. 木造もくぞう建築けんちくで、基礎きその上うえに据すえる横材よこざい。
2. 建築物けんちくぶつの最さい下部かぶにあり、上うえの重おもみを支ささえるもの。
3. 物事ものごとの基礎きそ。
4. 元々もともと。