from
Jargon File (4.4.4, 14 Aug 2003)
cross-post
vi.
[Usenet; very common] To post a single article simultaneously to
several newsgroups. Distinguished from posting the article repeatedly,
once to each newsgroup, which causes people to see it multiple times
(which is very bad form). Gratuitous cross-posting without a
Followup-To line directing responses to a single followup group is
frowned upon, as it tends to cause {followup} articles to go to
inappropriate newsgroups when people respond to various parts of the
original posting.
from
The Free On-line Dictionary of Computing (8 July 2008)
cross-post
[{Usenet}] To post a single article simultaneously to several
{newsgroups}. Distinguished from posting the article
repeatedly, once to each newsgroup, which causes people to see
it multiple times (which is very bad form). Gratuitous
cross-posting without a Followup-To line directing responses
to a single followup group is frowned upon, as it tends to
cause {followup} articles to go to inappropriate newsgroups
when people respond to only one part of the original posting.
[{Jargon File}]