Leveraged ETF
  
See: Exchange-Traded Fund (ETF).
An LETF is just an ETF...but with debt. So you can imagine owning an ETF on, say, the telecommunications industry, which is already, on its own, leveraged 3-4 times debt-to-EBITDA. But then add to this balance sheet volatility, the notion that you have an ETF that is itself leveraged 2:1.
So a given ETF, already leveraged 3:1, inside a fund leveraged 2:1, is then net leveraged 6:1.
If things go well, then wow, awesome...and if they don't, well...gather a bonfire of $100 bills and find someone who smokes to light the first match.