com·pas·sion (n.) - Genuine sympathy for and desire to help others who are suffering.
I'd like to add that compassion extends not just to those who are suffering in ways that we understand, but also to those who suffer in ways that we do not know. For example, someone can speak harshly towards me with unkind words and insults, which is a wrongful and hurtful action. It can be easy to retaliate with my own harsh words and judgment. But that is when I try to give "the benefit of the doubt." Perhaps that person is suffering in ways that I cannot see and cannot know; maybe her unkind words are a reaction to the pain or sorrow she is experiencing. It is not right for her to take her struggles out on me, but she is human and makes mistakes. When I think about it, I realize that I make similar mistakes, so rather than judge and insult her back, I should offer compassion and understanding. Sometimes a compassionate response is all a person needs to start being more patient and kind herself.