ALSO CALLED: Broadband Integrated Services Digital Network, BISDN, and B-ISDN
DEFINITION: BISDN is both a concept and a set of services and developing standards for integrating digital transmission services in a broadband network of fiber optic and radio media. BISDN will encompass frame relay service for high-speed data that can be sent in large bursts, the Fiber Distributed-Data Interface (Fiber Distributed-Data Interface), and the Synchronous Optical  … 
Definition continues below.

BROADBAND ISDN DEFINITION (continued): … BISDN is both a concept and a set of services and developing standards for integrating digital transmission services in a broadband network of fiber optic and radio media. BISDN will encompass frame relay service for high-speed data that can be sent in large bursts, the Fiber Distributed-Data Interface (Fiber Distributed-Data Interface), and the Synchronous Optical Network (Synchronous Optical Network). BISDN will support transmission from 2 Mbps up to much higher, but as yet unspecified, rates.

BISDN is the broadband counterpart to Integrated Services Digital Network, which provides digital transmission over ordinary telephone company copper wires on the narrowband local loop.
Broadband ISDN definition sponsored by SearchNetworking.com, powered by WhatIs.com an online computer dictionary