Affirmation
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
In practice
A solemn and formal declaration or asseveration that an affidavit is true, that the witness will teli the truth, etc., this being substituted for an oath in certain cases. A solemn religious asseveration in the nature of an oath.
1 GreenL Ev. § 371.