In Jainism, Chauvihar Upvas (often spelled as Chauvihar Upvaas) refers to a specific type of fasting or dietary restriction observed by Jains.

• Chauvihar means "fourfold renunciation." In this context, it signifies the renunciation of food and water after sunset until sunrise the next day.
• Upvas means fasting.

Chauvihar Upvas thus refers to a fast in which the practitioner does not consume any food or water from sunset until the next sunrise, and often, for the entire day of the fast, they abstain from all food and water. This is considered a stricter form of fasting compared to other types, such as Biyasan, Ekasana, or Bela.

Significance: Chauvihar Upvas is observed for spiritual purification, self-control, and as a means to progress on the path of non-attachment and liberation (moksha). It helps minimize himsa (violence) caused by eating and drinking at night when more living beings are present and less visible.

Summary: Chauvihar Upvas in Jainism is a fast in which one abstains from all food and water from sunset until the next day (or sunrise), practiced for spiritual discipline and non-violence.