The word benefact means to do good to someone or to give something for their benefit. There are many synonyms for benefact such as help, aid, assist, support, contribute, grant, donate, endow, bequeath, bless, and favor. These words suggest the act of giving or doing something for the betterment of others. Giving back to society is always an act of benefaction and a synonym for it could be philanthropy. Benefaction could also imply a sense of gratitude, so words like repay, reciprocate, acknowledge, and appreciate might be used for it. Overall, there are many different ways to express the idea of benefaction or doing good for others.