Roedy Green schreef:

Which website?  There is nothing like the TeX website.  There is only
one developer for TeX, and that is D.E. Knuth, and he doesn't actively
work on it any more.  There is LaTeX3, however (though active they may
be, there doesn´t seem to be much advance).

Anyway, as I said. Knuth uses it in the TeXbook and it is a TeX command.
 I can't find the definition now, but anyway it is used to keep lines
in a paragraph or table far enough from each other.

A nice qoute I found while looking for it:

"TeX has caused me to weep with frustration far more often than any
other piece of software. The full use of TeX requires an IQ in excess of
150. The plain TeX textbook is one of the most incomprehensible user
manuals ever written. The TeX language is one of the worst-designed and
incomprehensible languages ever invented. If there were any software
that could achieve similar results with less pain, I would use it. One
can only pray that some day someone will write a comprehensive
rationally thought-out front end for TeX and a user manual that assumes
an IQ less than 200. (Since gods are all in the mind, praying has no
hope of success, but it does relieve the pain a little.)"

Which is very true, but nevertheless shouldn't hold anybody from using
it, as indeed it does the best job there is.

And as Darryl said, look in a dictionary:  A structural element used to
brace or strengthen a framework by resisting longitudinal compression.

H.