Tread down is a phrase that can be used to convey different meanings based on the context. It can mean to trample on something, to suppress or oppress something, or even to conquer something. Some synonyms for the phrase include "crush," "flatten," "overpower," "subdue," "subjugate," "dominate," "trounce," and "vanquish." Each of these words carries a slightly different connotation, but all of them relate to the act of asserting control over something. It's important to choose the right synonym based on the context in order to accurately convey the intended meaning.