semé means 'sown
', and is used when part of a shield
does not contain some definite number, as one or three or eight, of an object, but has many small copies of the object strewn across it. By convention some of these are drawn cut off by the edge of the shield or of the bounding region.
When the object (technically the charge) being sown is a fleur-de-lys, the special term semé-de-lys is used. The main example is France Ancient, the original coat of arms of France, which was Azure semé-de-lys Or, that is blue with gold lilies. Later in the Middle Ages it was changed to France Modern, which has just three fleurs-de-lys on the field.