Plethron (Ancient Greek: πλέθρον, plural plethra) is an ancient unit of Greek measurement equal to 97 to 100 Greek feet (ποῦς, pous; c. 30 centimeters),[1][better source needed] although the measures for plethra may have varied from polis to polis.
[citation needed] This was roughly the width of a typical ancient Greek athletic running-track.
[2][full citation needed][non-primary source needed] A square plethron of c. 30 by 30 meters was used as the standard dimensions of a Greek wrestling square, since such competitions were held within the racing track in ancient Greece.
[citation needed] In other connotations, it functioned as the Greek acre, and varied in size to accommodate the amount of land a team of oxen could plow in a day.
[citation needed] The plethron continued to be used in the Byzantine Empire, where its variant uses were ultimately codified to refer to an area defined by sides of 100 feet or 40 paces (βῆμα, bema).