Plain English Meaning

A number on a sectional chart that tells you the highest thing — ground or man-made structure — inside that square of the map, so you know the lowest altitude that would clear everything in it.

Full Definition

Maximum Elevation Figures (MEFs) are values printed in each quadrangle on VFR sectional and terminal area charts that represent the highest elevation within that quadrangle, including terrain and the highest known obstruction (such as towers, antennas, or buildings), rounded up with a buffer to account for vertical accuracy and unknown obstacles. The figure is shown in thousands and hundreds of feet above mean sea level (MSL).