flush
1. To delete something, usually superfluous, or to abort an
operation.
"Flush" was standard {ITS} terminology for aborting an output
operation. One spoke of the text that would have been
printed, but was not, as having been flushed. It is
speculated that this term arose from a vivid image of flushing
unwanted characters by hosing down the internal output buffer,
washing the characters away before they could be printed.
2. To force temporarily buffered data to be written to more
permanent memory. E.g. flushing buffered disk I/O to disk, as
with {C}'s {standard I/O} library "fflush(3)" call. This
sense was in use among {BLISS} programmers at {DEC} and on
{Honeywell} and {IBM} machines as far back as 1965. Another
example of this usage is flushing a {cache} on a {context
switch} where modified data stored in the cace which belongs
to one processes must be written out to main memory so that
the cache can be used by another process.
[{Jargon File}]