ˌFifth Aˈmendment, the BrE AmE
1 . a part of the ↑ Constitution of the United States which states that you do not have to give information in a court of law which could be used against you, and that you cannot be put in prison or have your property taken away without a proper legal ↑ trial
2 . plead/take the Fifth (Amendment) to refuse to give information against yourself in a court of law. People in the US sometimes use this expression humorously when they do not want to answer a question:
‘I plead the Fifth’, Jack said, when his wife wanted to know where he had been.