1. Throw from a boat
   "The smugglers deep-sixed the contraband when they saw the coast guard approaching";
   - throw overboard
    
2. Toss out; get rid of
   "deep-six these old souvenirs!";
   - give it the deep six [informal]

Derived forms: deep-sixing, deep-sixed, deep-sixes

Type of: cast aside, cast away, cast out, chuck out, discard, dispose, fling, put away, throw, throw away, throw out, toss, toss away, toss out, wing