Caption is defined as …

a short piece of text under a picture that describes or explains what it is about. 

a relatively long work of narrative fiction, normally written in prose form, and which is typically published as a book. 

a piece of prose fiction that typically can be read in one sitting and focuses on a self-contained incident or series of linked incidents. 

a periodical publication containing written information about current events and is often typed in black ink with a white or gray background. 

a piece of writing in which the words are chosen for their beauty and sound and are carefully arranged, often in short lines which rhyme.