catchwords

/K AE1 CH W ER0 D Z/
noun
  1. 1

    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. 2

    A word or expression repeated until it becomes representative of a party, school, business, or point of view.

  3. 3

    Among theatrical performers, the last word of the preceding speaker, serving as a cue for the next speaker.

Source: https://en.wiktionary.org/wiki/catchword, https://en.wiktionary.org/wiki/catchwords