Red Dwarf, like many other science fiction series, developed its own distinct vocabulary. Words and phrases such as Hologrammatic, Dollarpound, Felis sapiens, Fuchal, Rogue Simulants, GELF, Space weevil and Zero G Football appear at various points during the series, highlighting a development in language, political climate, technology, evolution and culture in the future.
The series also famously employed a vocabulary of fictional expletives in order to avoid using potentially-offensive expletives in the show, and to give nuance to futuristic colloquial language. By far, the most famous example is 'smeg'. The word can be considered a substitute for either "shit" or "fuck" depending on circumstance, and so variations of the word include 'smeghead', 'smeg off' and 'smegging hell'. Grant and Naylor have stated that they invented the word "smeg", and that it has no connection with any similar real words, such as 'smegma' or the brand name that appears on the front of kitchen appliances. However, lexicographer Tony Thorne, in his 1990 Dictionary of Contemporary Slang (ISBN 0-7475-2856-X), reports instances of 'smeg' (and derivatives) being used as a term of 'mild contempt and even affection' among 'schoolboys, students and punks' as early as the mid-1970s — a decade or so prior to the inception of the Red Dwarf phenomenon — and unequivocally traces the etymology of the term back to 'smegma'. A character in the 1978 DEVO promotional video "The Men Who Make The Music" employs the term in the line "You're dying under Daddy's Cap, Smeghead."
Other invented expletives and euphemisms include 'goit' (one who is annoying or awkward) and 'gimboid' (one who is stupid or clumsy). Another term of abuse used once in the show was the word 'gwenlan', the last name of Gareth Gwenlan, a former BBC head of comedy who had once passed on the show.
