High Quality Content by WIKIPEDIA articles! In geometry, a cevian is any line segment in a triangle with one endpoint on a vertex of the triangle and the other endpoint on the opposite side. Medians, altitudes, and angle bisectors are special cases of cevians. The name cevian comes from the mathematician Giovanni Ceva, who proved a well known theorem about cevians which also bears his name. One example of a cevian would be the altitude of the triangle.