zillionthhttp://www.oed.com/dictionary/zillionth_n%3Ftab%3Dmeaning_and_usezillionth, n. & adj.
Revised 2021

zillionthnoun & adjective

colloquial (originally U.S.).
  1. noun
    1. 1940–
      A minute fraction of something.
      1. 1940
        The chatter arose again from this and that one that by adopting his idea there would be a zillionth better this and umpsteen [sic] fewer of that to contend with.
        Charleston (West Virginia) Gazette 20 August 6/1
      2. 1972
        We have strict controls on television... We don't hear a zillionth of what you hear.
        Good Housekeeping April 69/1
      3. 2018
        Suspiciously similar to lots of the brands above but a zillionth of the price.
        Daily Telegraph (Australia) (Nexis) 26 August 118
  2. adjective
    1. 1941–
      Used hyperbolically to emphasize that something has happened on many other occasions: ‘umpteenth’.
      1. 1941
        Getting ready to climb into an umpire's chair for the zillionth time in his life.
        Washington Post 3 September 19/4
      2. 1984
        For the zillionth time, the hardback edition only is credited in reviews.
        Listener 6 December 26/3
      3. 2010
        My 12-month-old son James was pressing the red button on a plastic tortoise which would initiate the zillionth play of Old MacDonald that day.
        Daily Telegraph 9 September 28/1

Originally published as part of the entry for zillion, n. & adj.

zillionth, n. & adj. was revised in March 2021.

zillionth, n. & adj. was last modified in July 2023.