platband

from The Century Dictionary.

• noun A border of flowers in a garden, or along a wall or the side of a parterre.
• noun In architecture: Any flat rectangular molding the projection of which is much less than its width; a fascia
• noun A lintel formed with voussoirs in the manner of an arch, but with the intrados horizontal—a common and vicious modern construction, but employed even in some Roman and medieval work in places where a true arch was not convenient, and when monoliths of sufficient size were not available. See cut of flat arch, under arch
• noun The fillets between the flutes of an Ionic or a Corinthian column.

from the GNU version of the Collaborative International Dictionary of English.

• noun A border of flowers in a garden, along a wall or a parterre; hence, a border.
• noun A flat molding, or group of moldings, the width of which much exceeds its projection, as the face of an architrave.
• noun A list or fillet between the flutings of a column.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A border of flowers in a garden, especially along a wall; a strip of turf forming a border.
• noun figuratively Any border.
• noun architecture A flat fascia on an architrave, or forming a border round a window, or a horizontal band along a wall.
• noun architecture A fillet on a column, between the flutings.
• noun rare A flat lintel over a door or window.