A luminaire comprises a relatively thin and flat light-emitting panel (1) having a light-emitting window (2) and, opposite said light-emitting window, a rear wall (3) with opposed edge surfaces (4, 14). At least one of the edge surfaces (4) is light transmitting and associated with a plurality of light sources (5, 5′, 5″, . . . ). Light originating from the light sources (5, 5′, 5″, . . . ) is spread in the panel (1). The invention is characterized in that a plurality of deformities (7, 7′, 7″, . . . ; 8, 8′, . . . ) is provided in the panel (1) for extracting light from the panel (1) via the light emission window (2). The deformities (7, 7′, 7″, . . . ; 8, 8′, . . . ) are clustered so as to form at least one light symbol (27; 28). The configuration of the clusters (17; 18) of deformities (7, 7′, 7″, . . . ; 8, 8′, . . . ) corresponds to the shape of the light symbol (27; 28). Preferably, the luminaire has a first and a second light-transmitting edge surface, with respectively, a first and a second plurality of light sources being associated with said surfaces. A first cluster of deformities only couples light from the first light source out of the panel, thereby forming a first light symbol, while a second cluster of deformities only couples light from the second light source out of the panel, thereby forming a second light symbol, independently of the formation of the first light symbol. The luminaire according to the invention provides independent lighting and coloring possibilities of light symbols in a single-panel luminaire.