catchword

From catch +‎ word.

• (UK) IPA^(key): /ˈkætʃwɜːd/

catchword (plural catchwords)

1. (printing, historical) A word under the right-hand side of the last line on a book page that repeats the first word on the following page.
2. (theater) The last word of a speech, serving as a cue for the next speaker.
3. A word or expression repeated until it becomes representative of a party, school, business, or point of view.
   • 2014 November, Najwa al-Qattan, “When mothers ate their children”, in International Journal of Middle East Studies, volume 46, number 4, →JSTOR, pages 719–736:

     The war itself has several names, including "the famine war" (ḥarb al-majā'a) and seferberlik, a Turkish word, meaning "travel by land," that began its wartime career as a reference to "military conscription" but quickly became a catchword for all the calamities and suffering experienced by civilians.

• (word under right-hand side): guide word, custos
• (word repeated to become representative): watchword