A ritual is a specialized act or event which is important to a culture, society, sect or individual. Rituals often involve groups of those who believe in what is being ritualized. Chanting, singing, dancing or praying is often involved in performing a ritual.
The inhabitants of Kaelon II practiced a ritual known as the Resolution when an individual approached his or her 60th birthday. During the Resolution, a ceremony was held in the person's honor touting the person's accomplishments and their noteworthy achievements. Once the celebration was complete, the individual committed a ritualistic suicide. (TNG: "Half a Life")