1. <communications> An abstraction referring to any flow of data from a source (or sender, producer) to a single sink (or receiver, consumer). A stream usually flows through a channel of some kind, as opposed to packets which may be addressed and routed independently, possibly to multiple recipients. Streams usually require some mechanism for establishing a channel or a "connection" between the sender and receiver.
2. <programming> In the C language's buffered input/ouput library functions, a stream is associated with a file or device which has been opened using fopen. Characters may be read from (written to) a stream without knowing their actual source (destination) and buffering is provided transparently by the library routines.
[IBM AIX 3.2 Communication Programming Concepts, SC23-2206-03].