interest

Where does the word "interest" come from? It comes from Medieval Latin interesse, passing through Old French before entering English (1400s).

Interest’s story begins in Medieval Latin: interesse meant “to concern, be between.” 'inter', between, plus 'esse', to be. By medieval, the word had taken hold in Old French as interest. Compensation owed. It reached English by 1400s as interest. Financial 'interest' was the charge for a loan. Today, interest means curiosity; money paid for a loan.

1. Stage 1 · Medieval Latin · medieval interesse "to concern, be between", 'inter', between, plus 'esse', to be.
2. Stage 2 · Old French · medieval interest "damages, concern", compensation owed.
3. Stage 3 · English · 1400s interest "legal claim; concern", financial 'interest' was the charge for a loan.