Affidavit, n.
Etymology: [LL. affidavit he has made oath, perfect tense of affidare. See Affiance, Affy.]
(Law)
A sworn statement in writing; a declaration in writing, signed and made upon oath before an authorized magistrate. Bouvier. Burrill.
Note: It is always made ex parte, and without cross-examination, and in this differs from a deposition. It is also applied to written statements made on affirmation.
Syn. -- Deposition. See Deposition.
Shades of meaning
Fernald has no entry of its own for affidavit; he lists it under oath, testimony.
Where he writes about it:
In the highest sense, as in a court of justice, "an oath is a reverent appeal to God in corroboration of what one says," ABBOTT Law Dict.; an affidavit is a sworn statement made in writing in the presence of a competent officer; an adjuration is a solemn appeal to a person in the name of God to speak the truth. — from oath
Deposition and affidavit denote testimony reduced to writing; the deposition differs from the affidavit in that the latter is voluntary and without cross-examination, while the former is made under interrogatories and subject to cross-examination. — from testimony