This is the 4068th most frequent Russian word.
несчастный
Unhappy; miserable.
In this sentence, 'несчастным' is used as an adjective to describe someone's emotional state.
Он выглядел очень несчастным после своего поражения.
He looked very unhappy after his defeat.
Here, 'несчастный' is used as an adjective to describe the nature of the accident, implying it's unfortunate.
Этот несчастный случай изменил её жизнь навсегда.
This unfortunate accident changed her life forever.
In this sentence, 'несчастный' is utilized as an adjective to express the pitiful or wretched condition of a person.