そこsoko
1.

The lowest part of an object that has a hollow or depressed shape, such as a container, where contents would settle.

2.

The foundational layer in a stack of items, indicating what is underneath or supporting all others.

3.

The extreme level reached below the water's surface or ground, often associated with depth in a physical or metaphorical sense.

4.

An underlying depth that is difficult to perceive or understand, often referring to the core of someone's feelings or thoughts.

5.

A metaphorical reference to the innate capacities or potentials of a person, which are not immediately apparent.

6.

The point at which economic conditions or prices reach their lowest, often used to describe market trends or downturns.

Example:

靴のがすり減ってしまった。

しんそこ心底shinsokoしんてい心底shintei
1.

The deepest feelings and thoughts that reflect one's true emotions and sentiments, often pertaining to authenticity and sincerity.

2.

The essential truth of one's heart or mind, often implying a profound understanding or insight into one's genuine feelings.

3.

The core of one's emotional state, where the most intimate and heartfelt intentions reside, suggesting a level of honesty that goes beyond superficial expressions.

Example:

彼は心底は善人だ。

てってい徹底tettei
1.

The quality of ensuring that actions and attitudes are not half-hearted, fully committed to a single principle or belief.

2.

The state of instructions or policies being disseminated fully and reaching every relevant aspect or individual.

3.

The characteristic of adhering consistently to a particular philosophy or mindset without deviation.

Example:

生産性はオートメーションの徹底によって向上する。

とうてい到底toutei
1.

An expression used to emphasize the impossibility or futility of a situation, often in conjunction with negative phrases, suggesting that no matter the effort, success cannot be achieved.

2.

A term that indicates the ultimate conclusion or end result of a situation, often used to highlight what is inevitable despite previous attempts or circumstances.

3.

A way to convey profound disbelief regarding the feasibility of an action or event, reinforcing that achieving it is entirely out of the question.

Example:

あなたの話は到底真実だと思えない。

こころkokoronoそこsoko
1.

The deepest part of one's emotions or consciousness, often associated with genuine feelings or thoughts.

2.

The true and sincere core of one's heart, where authentic feelings reside, free from falsehood or pretense.