To add to a thing what makes it fuller without changing what it is. Enrichment deepens rather than replaces.
Old French enrichir, en- plus riche (rich), of Frankish origin; to add richness without changing what a thing fundamentally is.
Its root travelled through French from Frankish, one people's own word for wealth carried into another tongue without displacing what was already spoken there. To enrich still works by that rule: what arrives adds, and nothing already present has to leave to make room for it.