Conspirer is a word that is often associated with negative actions, such as plotting or planning secretly with others to do something illegal or harmful. However, there are various synonyms to describe a person who conspires with others. Some key synonyms for the word conspirer include schemer, plotter, conniver, and colluder. Schemer and plotter suggest a person who makes a secret plan to achieve a particular goal. Meanwhile, a conniver is someone who is involved in a secret scheme, often for personal gain. Lastly, colluder is a term that refers to someone who participates with others in unauthorized actions or commits a crime with another person.