The defect is referred to as a recombination or trapping centre since it creates a energy level in the bandgap in that placein the crystal. Because of that energy level, it may trap a electron from the conduction band, which may loose some energy and reach that energy level, or it may trap a hole from the valence band. Or the trapping process can continue in such a way that it traps a electron from the conduction band and then a hole from the valence band and hence results in an effective recombination of the electron hole pair, so it can also be called as a recombination centre.