"Deep six" is a colloquial expression that refers to getting rid of something or someone. Synonyms for this phrase include "bury," "sink," "jettison," "dispose of," "eliminate," and "dump." Each of these synonyms has slightly different connotations; for instance, "bury" implies concealing something, "jettison" emphasizes the act of throwing something away, and "eliminate" suggests getting rid of a problem or obstacle. However, all of these synonyms share the sense of intentionally removing something from sight or consideration. So whether you're talking about a bad habit, a problematic employee, or an undesirable outcome, using one of these synonyms instead of "deep six" will add variety and nuance to your writing or speech.