In telecommunication, the term bandwidth compression has the following meanings:

• The reduction of the bandwidth needed to transmit a given amount of data in a given time.
• The reduction of the time needed to transmit a given amount of data in a given bandwidth.

Note: Bandwidth compression implies a reduction in normal bandwidth of an information-carrying signal without reducing the information content of the signal. This can be accomplished with data compression techniques.

Source: from Federal Standard 1037C and from MIL-STD-188