cap ‧ tion /ˈkæpʃ ə n/ BrE AmE noun [countable]
[ Date: 1700-1800 ; Origin: caption 'act of seizing or arresting, document allowing this' (14-19 centuries) , from Latin captio 'act of taking' , from capere ; ⇨ ↑ captive 1 ]
words printed above or below a picture in a book or newspaper or on a television screen to explain what the picture is showing ⇨ subtitle
—caption verb [transitive usually passive] :
a photograph of the couple captioned ‘rebuilding their romance’