There are many terms from classic and modern SF that remain unresearched, and the Historical Dictionary of Science Fiction will be continually updated, especially as additional resources are put online. Boing Boing is syndicating new entries from the HDSF on a regular basis. (Read the series introduction.)
An easy way to generate a science-fictional term is simply to slap the word space in front of a regular word. Thus, space armor, space car, space fleet, space navigator, and many others. Sometimes—as in these examples—the meanings are clear, but in other cases they can be more vague, thanks to the broadness of the sense of the base word.
One such example is space bum. The word bum has a number of related senses. The original meaning, from the 1860s, is 'a tramp; a vagrant; a scrounger', and is a shortening of the earlier bummer, deriving from a German word referring to an unemployed person. By the 1880s, the obvious derivative 'a contemptible person' arose, and by the 1930s, we see the weakened use 'a person who devotes time chiefly to a recreational activity' (as in ski bum). (The bum referring to the buttocks is an entirely different word, of uncertain origin, dating to the fourteenth century.)
Our first SF examples of space bum show up in the late 1930s, and was particularly common throughout the middle of the 20th century, reflecting all the nuances of the base word: idleness, aimlessness, vagrancy, worthlessness. While most of our examples come from traditional sources, we were pleased to find a particularly fun example in the 1987 SF spoof Spaceballs; any way to get Mel Brooks into a dictionary is a win in our book!