A more thorough explanation:

Definition: Mainsworn refers to a person who has made a false oath by placing their hand on a book. This term was commonly used in northern England in the past.

Example 1: John was accused of being mainsworn when he lied under oath during the trial.

Example 2: The witness was warned not to be mainsworn and to tell the truth during the court proceedings.

These examples illustrate how mainsworn was used to describe someone who made a false oath while placing their hand on a book. It was considered a serious offense and could result in legal consequences.