They could mean Common Unix Printing System CUPS.

CUPS is the software you use to print
from applications like the web browser
you are using to read this page. It
converts the page descriptions
produced by your application (put a
paragraph here, draw a line there, and
so forth) into something your printer
can understand and then sends the
information to the printer for
printing.

Now, since every printer manufacturer
does things differently, printing can
be very complicated. CUPS does its
best to hide this from you and your
application so that you can
concentrate on printing and less on
how to print. Generally, the only time
you need to know anything about your
printer is when you use it for the
first time, and even then CUPS can
often figure things out on its own.¹

¹http://www.cups.org/documentation.php/overview.html.