Definition of "ticker"

ticker

/ˈtɪkɚ/

noun
plural tickers
1. One who makes a tick mark.
  Quotations
  A teacher now is a typist, a printer, a laboratory assistant, a designer of work sheets and booklets, a form-filler, a ticker of boxes and a sender of returns to faculty heads, to head teachers, to education authorities and to the Ministers […]
  1992, Parliamentary Debates (Hansard)
2. A measuring or reporting device, particularly one which makes a ticking sound as the measured events occur.
3. A ticker tape, either the traditional paper kind or a scrolling message on a screen.
4. (slang) A heart, especially a human one.
5. (slang) A watch (timepiece).
  Quotations
  A right nice ticker it was. Real gold.
  2011, Maggie MacKeever, The Tyburn Waltz
6. (birdwatching, slang) A birdwatcher who aims to see (and tick off on a list) as many bird species as possible.