Definition of captions:
(n) :
A title or brief explanation attached to an illustration, cartoon, user interface element, etc.
(n) :
(cinematography, television) A piece of text appearing on screen as a subtitle or other part of a film or broadcast, describing dialogue (and sometimes other sound) for viewers who cannot hear.
(n) :
(typography) The descriptive heading or title, of a document or part thereof.
(v) :
To add captions to a text or illustration.
(v) :
To add captions to a film or broadcast.
(n) :
(law) The section on an official paper (for example, as part of a seizure or capture) that describes when, where, and what was taken, found or executed, and who authorized the act.