1911 Encyclopædia Britannica/Caption

CAPTION (Lat. captio, a taking or catching), a term still used in law, especially Scots, for arrest or apprehension. From the obsolete sense of a catching at any possible plea or objection comes the adjective “captious,” i.e. sophistical or fault-finding. The term also has an old legal use, to signify the part of an indictment, &c., 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.