means An earlier action, decision, or event that serves as a guide or rule for how similar situations should be handled later.

from From Latin praecedens, the present participle of praecedere, 'to go before' — built from prae- ('before') and cedere ('to go,' the same root that walks through 'proceed,' 'recede,' and 'exceed'). It arrived in English through Old French in the late Middle Ages, first meaning simply 'a thing that comes before,' and settled into its legal sense — the case that future cases must follow — as it became the spine of common law.