The Collaborative International Dictionary of English v.0.48:

Ticker \Tick"er\ (t[i^]k"[~e]r), n. [See Tick.]
   1. One who, or that which, ticks, or produces a ticking
      sound, as a watch or clock, a telegraphic sounder, etc.
      [1913 Webster]

   2. A telegraphic receiving instrument that automatically
      prints off stock quotations (stock ticker), market
      report, or other news on a paper ribbon or "tape."
      [Webster 1913 Suppl.]

   3. an electronic instrument receiving information by
      transmision from a remote source and displaying it in
      readable fashion, not necessarily on paper tape (e.g. on a
      video display terminal or moving ribbon of electronically
      controlled lights).
      [PJC]

   4. The heart. [Colloq.]
      [PJC]

   Ticker tape Tape from or designed to be used in a stock
      ticker, usu. of paper and being narrow but long.

   Stock ticker, an electro-mechanical information receiving
      device connected by telegraphic wire to a stock exchange,
      and which prints out the latest transactions or news on
      stock exchanges, commonly found in the offices of stock
      brokers. By 1980 such devices were largely superseded by
      electronic stock quotation devices.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

stock ticker
    n 1: a character printer that automatically prints stock
         quotations on ticker tape [syn: ticker, stock ticker]