[f. same source as TICK v.1 or sb.3] An imitation of the sound of a clock or watch; ticking; in quot. 1805, throbbing of the pulse. So Tick-a-tack. (Cf. TICK-TACK, TICK-TICK.)

1

1805.  in Spirit Pub. Jrnls., IX. 243. Munro shall count of pulse his tick-a-tick.

2

1883.  D. R. Sellars, in Mod. Scot. Poets, VI. 157.

        ‘Tick-a-tick! tick-a-tick!’
  My old clock’s voice I hear.

3

1898.  Doyle, in Speaker, 5 March, 298/1. The clock goes tick-a-tack.

4