Colluder refers to someone who works together with others in secret to deceive or manipulate someone or something. There are many words that are synonymous with colluder, including conspirator, accomplice, ally, associate, co-conspirator, confederate, partner, and collaborator. All of these words suggest a close collaboration or working relationship to achieve a common goal or objective, often through deceitful means or intentions. These words are often used to describe individuals who are involved in criminal or unethical activities, and they are often used in legal and political contexts to describe individuals who have engaged in activities that have violated the law or ethical standards.