The story
Coined in 1985 by Elias James Corey from retro-synthon (Elias James Corey, Alan K. Long, Stewart D. Rubenstein, “Computer-assisted analysis in organic synthesis”, Science, 1985, 228(4698), p. 408-418 doi 10.1126/science.3838594).
Etymology from Wiktionary, CC BY-SA 4.0.