The term "unimpeachable" refers to something or someone that is completely reliable and cannot be doubted, challenged, or called into question. It is used to describe a person's character, testimony, evidence, or source of information that is considered to be beyond reproach or criticism. An unimpeachable statement or action is one that is not subject to any doubt or suspicion and is considered to be absolutely true or correct. In legal contexts, unimpeachable evidence or witness testimony is admissible in court and cannot be contested or discredited by the opposing party.
