Defined risk means your maximum possible loss is fixed and cannot be exceeded regardless of how far the underlying moves. It is established at entry.  

Strategies with defined risk include Bull Call Spread, Bear Put Spread, Iron Condor, Iron Butterfly, Long Straddle, Long Strangle. These are generally safer for traders who want to know exactly how much they can lose.  

Strategies with undefined or theoretically unlimited risk include Short Straddle, Short Strangle, naked Sell Call, naked Sell Put, and Ratio Spreads beyond the hedge point. The platform clearly labels risk parameters for every strategy before execution.