Unsecured

See: Debenture.

A security (usually a bond) that is unsecured by anything structural is a debenture.

So what's "secured"? Like...if an oil company borrows $2 billion and says, "If we don't pay every penny on interest and principal, then you, Bank of Qatar, can take back this oil rig; you'll then own it." That's a secured loan. Likely safe, and carries a low interest rate.

The unsecured flavor? Just a handshake. "You know me. I know you. (I know where your children go to school, so you'll pay me back, rrrright?)"

Unsecured loans. Risky. High interest rates. Prayer.