The Collaborative International Dictionary of English v.0.48:

bandwidth \band"width`\ n.
   The maximum rate of information transfer (measured in
   bits/second) that can be carried by a communication channel.
   "The bandwidth of an analog telephone line is less than 100
   kilobits per second."
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

bandwidth
    n 1: a data transmission rate; the maximum amount of information
         (bits/second) that can be transmitted along a channel

The Jargon File (version 4.4.7, 29 Dec 2003):

bandwidth
 n.

    1. [common] Used by hackers (in a generalization of its technical meaning)
    as the volume of information per unit time that a computer, person, or
    transmission medium can handle. ?Those are amazing graphics, but I missed
    some of the detail ? not enough bandwidth, I guess.? Compare low-bandwidth
    ; see also brainwidth. This generalized usage began to go mainstream
    after the Internet population explosion of 1993-1994.

    2. Attention span.

    3. On Usenet, a measure of network capacity that is often wasted by
    people complaining about how items posted by others are a waste of
    bandwidth.


The Free On-line Dictionary of Computing (30 December 2018):

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)