Source : WordNet®

bandwidth
     n : a data transmission rate; the maximum amount of information
         (bits/second) that can be transmitted along a channel

Source : Free On-Line Dictionary of Computing

bandwidth
     
         The difference between the highest and lowest
        frequencies of a transmission channel (the width of its
        allocated band of frequencies).
     
        The term is often used erroneously to mean {data rate} or
        capacity - the amount of {data} that is, or can be, sent
        through a given communications circuit per second.
     
        [How is data capacity related to bandwidth?]
     
        [{Jargon File}]
     
        (2001-04-24)