noun

• (of a signal) The width of the smallest frequency band within which the signal can fit.
• (networking, informal) The rate of data flow in digital networks typically measured in bits per second; the bitrate.
  "While comm buoys allow rapid transmission, there is a finite amount of bandwidth available. Given that trillions of people may be trying to pass a message through a given buoy at any one time, access to the network is parceled out on priority tiers."
• (informal) The capacity, energy or time required.
  "I think it's a worthy project, but I just don't have the bandwidth right now."
• (graph theory) The minimum, over all orderings of vertices of a given graph, of the length of the longest edge.