The name DEXTER comes from the phrase DESKside clusTER, the internal name of the project of building our own small supercomputer. Yes, we know. The X is missing but if you try to say deskside cluster fast, it is almost there.
Now you see it is quite difficult to pronounce it, especially several times a day. We needed a shorter version so it became DEXTER.
Since it is a proper small supercomputer for personal use for professionals, then we named it DEXTER personal cluster computer.