The story
Coined by Michelle Fine in her 1994 paper Working the hyphens: Reinventing the self and other in qualitative research, which was published in N. K. Denzin & Y.S.Lincoln (Eds.), Handbook of qualitative research; in reference to the grammatical use of hyphens to represent a unified form of two discrete concepts, such as in blue-green or hunter-gatherer.
Etymology from Wiktionary, CC BY-SA 4.0.