What is defined as 'perjury'?

Perjury is specifically defined as the act of deliberately providing false testimony while under oath during legal proceedings. This definition stresses the importance of truthful communication in the legal system, as oath-taking signifies a commitment to tell the truth. When an individual lies while testifying, it undermines the integrity of the judicial process, as the court relies on accurate information to make fair and just decisions.

The other choices do not capture the essence of perjury. Providing honest testimony under oath reflects the proper conduct expected in a court, while giving incomplete information does not necessarily equate to lying under oath. Admitting guilt during a trial, on the other hand, is not connected to the concept of perjury, as it involves an acknowledgment of wrongdoing rather than deceit. Hence, the correct answer highlights the affirmative action of lying while sworn to tell the truth.