Source : WordNet®

pipeline
     n 1: gossip spread by spoken communication; "the news of their
          affair was spread by word of mouth" [syn: {grapevine}, {word
          of mouth}]
     2: a pipe used to transport liquids or gases; "a pipeline runs
        from the wells to the seaport" [syn: {line}]

Source : Free On-Line Dictionary of Computing

pipeline
     
         A sequence of {functional units} ("stages")
        which performs a task in several steps, like an assembly line
        in a factory.  Each functional unit takes inputs and produces
        outputs which are stored in its output {buffer}.  One stage's
        output buffer is the next stage's input buffer.  This
        arrangement allows all the stages to work in parallel thus
        giving greater throughput than if each input had to pass
        through the whole pipeline before the next input could enter.
     
        The costs are greater latency and complexity due to the need
        to synchronise the stages in some way so that different inputs
        do not interfere.  The pipeline will only work at full
        efficiency if it can be filled and emptied at the same rate
        that it can process.
     
        Pipelines may be synchronous or asynchronous.  A synchronous
        pipeline has a master clock and each stage must complete its
        work within one cycle.  The minimum clock period is thus
        determined by the slowest stage.  An asynchronous pipeline
        requires {handshaking} between stages so that a new output is
        not written to the interstage buffer before the previous one
        has been used.
     
        Many {CPU}s are arranged as one or more pipelines, with
        different stages performing tasks such as fetch instruction,
        decode instruction, fetch arguments, arithmetic operations,
        store results.  For maximum performance, these rely on a
        continuous stream of instructions fetched from sequential
        locations in memory.  Pipelining is often combined with
        {instruction prefetch} in an attempt to keep the pipeline
        busy.
     
        When a {branch} is taken, the contents of early stages will
        contain instructions from locations after the branch which
        should not be executed.  The pipeline then has to be flushed
        and reloaded.  This is known as a {pipeline break}.
     
        (1996-10-13)