catchline

[ kach-lahyn ]
/ ˈkætʃˌlaɪn /

noun

a word, phrase, or sentence used, especially in advertising or journalism, to arouse or call attention.
a line in which a catchword appears.
a line of lesser importance, set shorter or sometimes in smaller type than the lines above and beneath it.
Theater. a line of comic dialogue expected to elicit laughter.

Origin of catchline

First recorded in 1865–70; catch + line1