What is meridian definition?

Meridian can refer to two different things:

1. A meridian is a line of longitude that circles the Earth from the North Pole to the South Pole, passing through the geographic poles (the points where the Earth's axis of rotation intersects with its surface).

2. In traditional Chinese medicine, meridians (also called energy channels or pathways) are thought to be channels through which energy (called qi or chi) flows throughout the body. There are 12 primary meridians and 8 secondary meridians in the human body, each associated with a different organ system. Acupuncture and acupressure are techniques used to stimulate points on these meridians to regulate the flow of energy and promote healing. However, the existence and function of these meridians is not recognized by modern science.