Refers to a physical foundation (of a building, structure) or a figurative basis (of an argument, system, relationship).
If the foundation of the house is not solid, it will collapse in an earthquake.
Trust is the basis of a good relationship.
from the beginning; by nature; originally
Used adverbially, often in negative contexts, to mean 'in the first place' or 'fundamentally'. Similar to 元々, but with a nuance of inherent impossibility or unsuitability.
See also: もともと
He is, by nature, not good at speaking in public.
That plan was impossible from the outset.
They built the foundation of the new company.
A plan like that is impossible from the outset.
That experience became the foundation of his success.
There's no way I can finish that much work to begin with.
The company's foundation was shaken when the fraud came to light.
土台 often names a physical foundation or figurative groundwork, whereas 基盤 sounds more formal and is common in policy, business, and technical contexts.
土台 usually describes a literal, structural base (like a house's foundation), while 下地 more often refers to abstract preparatory conditions or skills.
土台 is a concrete, everyday word for a physical or metaphorical foundation, while 基 is formal and literary in tone.