1. noun /ˈkæp.ʃn/
a) The descriptive heading or title of a document or part therof
The caption and asportation must be felonious.
2. verb /ˈkæp.ʃn/
a) To add captions to a text or illustration.
Only once the drawing is done will the letterer caption it.
b) To add captions to a film or broadcast.
Wikipedia foundation.