A VARIATION OF GIVING (SOMEONE) THE DEEP-SIX, REJECTING, NEGATING OR ABANDONING; DISPOSING OF DEFINITIVELY. THE ORIGIN OF THIS PHRASE IS NAUTICAL; BURIALS AT SEA ARE MADE IN WATER MORE THAN SIX FATHOMS DEEP (A FATHOM IS A NAUTICAL UNIT OF LENGTH EQUAL TO SIX FEET OF WATER).