ze·​roth | \ˈzē-(ˌ)rōth, ˈzir-(ˌ)ōth\

Definition of zeroth 

: being numbered zero in a series also : zero sense 1 the zeroth power of a number

Zeroth and Ranking

You don't have to be a rocket scientist to use zeroth, but the word, which was coined by physicists 120 years ago, does often show up in scientific contexts. (It comes from zero, which is itself from Arabic ṣifr.) These days zeroth is frequently used to suggest a level of importance that is even higher than first. Renowned Soviet physicist Lev Landau used zeroth this way when he classified all the famous physicists according to the relative value of their contributions to science. He put Niels Bohr and Max Planck, for example, right up there in the first class, and lesser-rated physicists in the second through fifth classes. Where did he think Albert Einstein and Isaac Newton belonged? They were unmatched, he felt, so they went in his zeroth class.

First Known Use of zeroth

1896, in the meaning defined above

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The first known use of zeroth was in 1896

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by force of circumstances

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