A more thorough explanation:

A coconspirator is a person who is involved in a criminal conspiracy with another person. They are also known as a fellow conspirator.

For example, if two people plan to rob a bank together, they are both coconspirators in the crime.

Another term related to coconspirator is an unindicted coconspirator. This refers to a person who is identified by law enforcement as a member of a conspiracy but has not been named in the indictment.

For instance, if the police arrest one person for a crime and identify another person as an unindicted coconspirator, any statement made by the unindicted coconspirator in the course of the conspiracy can be used as evidence against the indicted defendant.

In summary, a coconspirator is someone who is involved in a criminal conspiracy, and an unindicted coconspirator is someone who is identified as a member of the conspiracy but not named in the indictment.