What does the term map scale mean?

A map scale is the amount that the drawing compares with an actual measurement. ie - one inch on the map may be equivalent to a mile. If it is a very detailed map then a mile may be as much as 4 inches (as on British Ordnance Survey maps.) On a page of an actual atlas showing a whole country, one inch can be 500 ore even a thousand miles. The scale is usually defined on the lower right corner of the map.