tick tack

tick tack (countable and uncountable, plural tick tacks)

1. (onomatopoeia) The sound of repeated tapping, knocking, or clicking.
   • 1870, Charles Bilton, “The household friend”, in The Class and Standard Series of Reading Books, Book IV, Special lessons for girls, page 199:

     But come to the clock, Mary. Remember, our lives are short, and they contain only a certain number of "tick tacks;" we cannot, therefore, afford to waste them.

   • 1992, William Russell Bascom, African Folktales in the New World, page 98:

     Nancy took Tacoma to a cow. Nancy went in first and cut his bag full. He told Tacoma not to cut the thing that went "tick, tack," but Tacoma cut it and the cow fell down dead.

2. (countable) A device used to tap on a window or door from a distance.
   • 1907, Nelson Lloyd, “The last ghost in Harmony”, in Scribner's Magazine‎, volume 41:

     I got me a hammer and nails with the heavy lead sinker offen my fishnet, and it wasn't long before the finest tick-tack you ever saw was working against the Spiegelnails' parlor window, with me in a lilac-bush operating the string that kept the weight a-swinging.

3. (UK, uncountable) Alternative form of tic-tac, a sign language used by bookmakers.