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zeroth

[zeer-ohth]
adjective
  1. coming in a series before the first: the zeroth level of energy.

Origin of zeroth

First recorded in 1895–1900; zero + -th1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for zeroth

zeroth

adjective
  1. denoting a term in a series that precedes the term otherwise regarded as the first term

Word Origin for zeroth

C20: from zero + -th ²
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