Torture vs Sadness - What's the difference?

Torture is a related term of sadness.

is .

(uncountable) the state or emotion of being sad.

(wikipedia torture)

(en noun)

Intentional causing of somebody's experiencing agony.

Using large dogs to attack bound, hand-cuffed prisoners is clearly torture .

In every war there are acts of torture that cause the world to shudder.

People confess to anything under torture .

(chiefly, literary) The "suffering of the heart" imposed by one on another, as in personal relationships.

Every time she says 'goodbye' it is torture !

* torture chamber *

(tortur)

To intentionally inflict severe pain or suffering on (someone).

People who torture often have sadistic tendencies.

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(wikipedia sadness)

(uncountable) The state or emotion of being sad.

(countable) An event in one's life that causes sadness.

She has experienced many sadnesses in her forty years.

* (state of being sad) forlornness, melancholy * (event causing sadness) misfortune, woe