The invention relates to an illuminant (23) and a socket (20) for a lamp (15). The features of the socket (20) can be implemented also independently of the features of the illuminant (23). The illuminant (23) has a preferably planar illumination surface (24). One or more semiconductor lighting elements are arranged within an illuminant housing (30). The illuminant connection device (70) required for mechanical and electrical connection to the socket (20) is provided on the rear face (66) of the illuminant (23), said rear face (66) lying opposite the illumination surface (24). The dimensions of the illuminant are preferably greater than the dimensions of the socket (10) such that the illuminant (23) fully covers the socket when looking onto the illumination surface (24), resulting in a particularly appealing look. Said socket and illuminant (23) modularly achieve large total illumination surfaces in a lamp (15) and an appealing overall appearance in a very simple manner.
