median

1. A line segment joining the vertex of triangle to the midpoint of the opposing side.
2. A number separating the higher half from the lower half of a data sample, population, or probability distribution. The median of a finite list of numbers can be found by arranging all the observations from lowest value to highest value and picking the middle one (e.g., the median of {3, 3, 5, 9, 11} is 5). If there is an even number of observations, then there is no single middle value; the median is then usually defined to be the mean of the two middle values.
3. The area separating two lanes of opposite-direction traffic. (US)

Plural medians