1. A data compression technique in which some data is deliberately discarded to achieve massive reductions in the size of the compressed file. Lossy compression techniques can reduce a file to 1/50 of its former size (or less), compred to the average of one-third achieved by lossless compression techniques. Lossy compression is used for graphics files in which the loss of data - such as information about some of the graphic's several million colors - isn't noticeable. An example is the JPEG compression technique.see lossless compression. From QUECID