white space n. an under-served business market or undeveloped product category. (source: Double-Tongued Dictionary)
Further reading
Old. Elderly. Senior. Why are we so uncomfortable when we talk about reaching a certain point in life? An 82-year-old seeks a more positive term to describe how she feels about her age. And: a linguist helps solve a famous kidnapping case, using the...
Doesn’t “white space” derive from 18/19C Euro-American maps of the world, white being the designation for uncolonized/uncivilized? See for example the beginning of Conrad’s Heart of Darkness where Marlowe remembers being a young adventurous boy looking at a map in which parts of Africa appear “a blank space of delightful mystery—a white patch for a boy to dream gloriously over.”
I don’t know about “derive” since “white space” or “blank space” in a non-jargon sense is a common enough term. I don’t think either can be said to be a term of art for cartography. Here, though, I think we are dealing with a very specific piece of jargon which is well beyond, say, “white space” as an artist’s tool, and is clearly and specifically a term of art.