"Tamp down" is a phrasal verb that means to reduce or suppress something. There are several synonyms for this phrase, including "quell," "subdue," "restrain," "moderate," "repress," "diminish," "hold back," "soften," and "temper." These words can be interchanged with "tamp down" depending on the context of the sentence. For example, instead of saying "I need to tamp down my anger," you could say "I need to quell my anger" or "I need to restrain my anger." Using synonyms like these can help to make writing more interesting and varied, while still conveying the same meaning.