This is the 17409th most frequent Turkish word.
üzüntüsünü
"Üzüntüsünü" means "his/her sorrow" or "his/her sadness."
In this sentence, 'üzüntüsünü' is used as the object of the verb 'anlattı, referring to a specific feeling of sadness.
Arkadaşına, kaybolan kedisinin üzüntüsünü anlattı.
He told his friend about the sadness he felt for his lost cat.
Here, 'üzüntüsünü' is again the object, emphasizing the individual's action of expressing an emotion.
Üzüntüsünü gizlemeyerek herkesle paylaştı.
She openly shared her sadness with everyone without hiding it.
In this example, 'üzüntüsünü' associates the word with 'babası', showing possession and relating to the emotion visible on his face.