Apple’s server version of the Macintosh, a 1U rack-mounted server, presently containing one or two G5 processors and up to 1.2TB of disk space. The machines ship with Mac OS X Server edition, known as “OSXS.”

Oh, it’s “Xserve,” not “XServe” or “xServe.” And, technically, it’s an “Xserve G5,” or, at least, current models are.

It used to be a joke that I have four of them in the server room at the lab.

There’s also the Xserve RAID, an enclosure for containing 14 SATA hard drives, up to 5.6TB. It connects via fiber channel to Macs and PCs.