next after the eighty-ninth; being the ordinal number for 90.
being one of 90 equal parts.


a ninetieth part, especially of one (1/90).
the ninetieth member of a series.

Origin of ninetieth

before 1100; Middle English nyntithe, Old English nigenteotha. See ninety, -eth2 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for ninetieth

Contemporary Examples of ninetieth

  • Neither retirement nor a ninetieth birthday slowed his publication rate.

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    Peter Stothard

    August 27, 2010

Historical Examples of ninetieth

British Dictionary definitions for ninetieth



(usually prenominal)
  1. being the ordinal number of ninety in numbering or counting order, position, time, etc. Often written: 90th
  2. (as noun)the ninetieth in succession


  1. one of 90 approximately equal parts of something
  2. (as modifier)a ninetieth part
the fraction equal to one divided by 90 (1/90)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for ninetieth

late 14c., nyntithe; see ninety + -th (1). Replaced Old English nigenteoþan.

Online Etymology Dictionary, © 2010 Douglas Harper