What is Caption?

Legal Definition
Caption was a term used (especially in Scotland), for arrest or apprehension.

Caption also has an old legal use, to signify the part of an indictment, etc., which shows where, when and by what authority it is taken, found or executed; so its opening or heading. From this is derived the modern sense of the heading of an article in a book or newspaper.

In accordance with the American Heritage Dictionary, the word is still used in the United States to indicate: "the heading of a pleading or other document that identifies the parties, court, term, and number of the action."
-- Wikipedia
Legal Definition
Practice. That part of a legal instrument, as a 'Commission, indictment, &c., which shows where, when, and by what authority it was taken, found or executed. As to the forms and requisites of captions, see 1 Murph. 281; 8 Yerg. 514; 4 Iredell, 113; 6 Miss,. 469; 1 Scam. 456; 5 How. Mis. 20; 6 Blackf. 299; 1 Hawks, 354; 1 Brev. 169.

2. In the English practice, when an in ferior court in obedience to the writ of certiorari, returns an indictment into the K. B. , it is annexed to the caption, then called a schedule, and the caption concludes with stating, that " it is presented in manner and form as appears in a certain indictment thereto annexed, " and the caption and indictment are returned on separate parch ments. 1 Saund. 309, n. 2. Vide Dane's Ab. Index, h. t.

3. Caption is another name for arrest.
-- Bouviers Law Dictionary
Legal Definition
In practice. That part of a legal instrument, as a commission, indictment, etc., which shows where, when, and by what authority it is taken, found or executed. State v. Sutton, 5 N. C. 281; U. S. v. Beebe, 2 Dak. 292, 11 N. W. 505; State v. Jones, 9 N. J. Law, 365, 17 Am. Dec. 483.

When used with reference to an indictment, caption signifies the style or preamble or commencement of the indictment; when used with reference to a commission, it signifies the certificate to which the commissioners' names are subscribed, declaring when and where it was executed. Brown. The caption of a pleading, deposition, or other paper connected with a case in court, is the heading or introductory clause which shows the names of the parties, name of the court, number of the case on the docket or calendar, etc. Also signifies a taking, seizure, or arrest of a person. 2 Salk. 498.

The word in this sense Is now obsolete in English law. In Scotch law. Caption is an order to incarcerate a debtor who has disobeyed an order, given to him by what are called "letters of horning," to pay a debt or to perform some act enjoined thereby. Bell.
-- Black's Law Dictionary
Legal Definition
A taking; a seizure; the heading of a document.
-- Ballentine's Law Dictionary