\Plat"band`\, n. [F. plate-bande; plat, plate, flat, level + bande a band.] 1. A border of flowers in a garden, along a wall or a parterre; hence, a border. 2. (Arch.) (a) A flat molding, or group of moldings, the width of which much exceeds its projection, as the face of an architrave. (b) A list or fillet between the flutings of a column.