There are several synonyms for the term "federal prison" that are commonly used in the criminal justice system. One of the most frequently used synonyms is "penitentiary," which refers to a high-security prison designed to hold the most dangerous and violent criminals. Another synonym for "federal prison" is "correctional facility," which is a more general term that can refer to any facility designed to hold individuals who have been convicted of a crime. Other synonyms for federal prison include "prison camp," "detention center," and "jail." Each of these terms carries slightly different connotations, so it's important to use the correct terminology when discussing the criminal justice system.