Sorrow
Part of speech: noun
Definition: unhappiness, woe An instance or cause of unhappiness.
Part of speech: verb
Definition: To feel or express grief.
Example sentence: There are no words to express my sorrow and regret for the pain I have caused others by words and actions. To the people I have hurt, I am truly sorry.
Sorrowfulness
Part of speech: noun
Definition: The quality or state of sorrow; sadness.