/prɪˈkəːsə/
noun
1 A person or thing that comes before another of the same kind; a forerunner.
1.1 A substance from which another is formed, especially by metabolic reaction.
Origin
Late Middle English: from Latin praecursor, from praecurs- ‘preceded’, from praecurrere, from prae ‘beforehand’ + currere ‘to run’.
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I hope it will not come as a surprise that the precursor is the one who arrives first. In a race that person is called the "winner".
