Here is the definition of "precedent" from Merriam Websters dictionary:
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precedent
1 of 2
pre·ce·dent
pri-ˈsē-dᵊnt ˈpre-sə-dənt
Synonyms of precedent
: prior in time, order, arrangement, or significance
precedent
2 of 2
prec·e·dent
ˈpre-sə-dənt
1
: an earlier occurrence of something similar
2
a
: something done or said that may serve as an example or rule to authorize or justify a subsequent act of the same or an analogous kind
a verdict that had no precedent
b
: the convention established by such a precedent or by long practice
3
: a person or thing that serves as a model