Step 1: Understand the meaning of the given word.
An affidavit is a written statement confirmed by oath or affirmation, used as evidence in a court of law.
Step 2: Identify the opposite idea.
An affidavit represents a truthful, sworn statement.
The opposite would involve a false or defamatory statement.
Step 3: Examine the options.
Affirmation: a formal declaration — similar in meaning
Slander: a false spoken statement damaging a person’s reputation — opposite in nature ✔
Oath: a solemn promise — similar in meaning
Testimony: evidence given under oath — similar in meaning
Step 4: Final conclusion.
The word opposite in meaning to affidavit is slander.