When Rimmer needed to identify an antivirus to the chameleonic microbe eating Red Dwarf, he crossed into a mirror universe where everything was opposite. Heading to the science labs, he asked Kochanski's duplicate to identify the antidote, but she was obviously not a scientist. She told "Captain Rimmer" that he would have to speak to the Professor.
The Professor (whose name, if any, was never used) was a Felinoid genius who wore dowdy clothes, everything The Cat was not. He had a tweed jacket, a white shirt and a bow tie. His hair was going grey and he wore spectacles, all of which made him look like a typical eccentric scientist.
He identified the antidote as an alkali called Cesiumfranciolithicmyxialobidiumrixydixydoxidrexidroxhide. Rimmer was astounded that he could pronounce it, when The Cat was such a dunce. He asked the Professor to write the name down, which required an extremely long piece of paper. ("Only The Good...")
Behind the scenes
Danny John-Jules was told by Doug Naylor that he did not have to learn how to say the antidote's name perfectly, but just make it up as he went. John-Jules refused to improvise and learned to say the long name flawlessly.
This meant that the rest of the cast had to learn it just as well for the scene where they must all recognise the alkali. After all that hard work, the scene was cut from the finished episode, much to their dismay. Only John-Jules is heard to mention the full name.