From Latin 'usura' (use, interest) — originally any loan interest; 'excessive' came from medieval theology.
The practice of lending money at unreasonably high rates of interest; historically, the charging of any interest on a loan.
From Anglo-Norman French 'usurie,' from Medieval Latin 'ūsūria,' from Latin 'ūsūra' (use, enjoyment of property, interest on a loan), from 'ūsus' (use), past participle of 'ūtī' (to use). The original meaning was simply 'a charge for the use of money' — interest. The condemnatory sense developed because medieval Christian and Islamic theology prohibited charging interest on loans, regarding it as profiting from another's need. The shift from 'interest' to 'excessive interest' reflects this moral evolution. Key roots: ūsūra (Latin: "use, interest"), ūtī (Latin: "to use").
The word 'usury' originally just meant 'interest' — any charge for lending money. In Dante's 'Inferno,' usurers are punished in the seventh circle of Hell alongside blasphemers, because charging interest was considered an offense against God's natural order: money was supposed to be barren, not breed more money. Shakespeare's Shylock is literature's most famous usurer, though his 'pound of flesh' is not interest but a bond penalty.