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SUPREMACY Definition & Meaning - Merriam-Webster

Websters 1828 - Webster's Dictionary 1828 - Supremacy

The word supremacy comes from Old French supreme (15th century) and directly from Latin supremus "highest," superlative of superus "situated above," from super "above". 

The term "supremacy" in the context of the English monarchy first appeared in a formal, political capacity with the Act of Supremacy in 1534, which established the King as the supreme head of the Church of England.  This parliamentary act made King Henry VIII the supreme head of the Church of England, severing ties with the Pope. 

According to the Oxford English Dictionary (OED), the noun "supremacy" was first used in English in a non-political context was in recorded evidence dating to 1540 in the writings of Richard Taverner.  According to the Oxford English Dictionary (OED), the adjective form of "supremacy" is supremacist, and was first used in the 1890s.

Examples of "supremacy" used in a sentence: 
"It was crushed by Google Search's supremacy and closed in 2014." 
"Clark said divisions in the U.S. are linked to the same cause: white supremacy." 
"But she does not put her proposals in the context of a global struggle for supremacy." 
"How long before it asserted its economic supremacy and crushed British business overseas? 
"The supremacy of the Boston Celtics of the late 1950s and 1960s was led by Bill Russell." 
"The era of Green Bay Packers supremacy under coach Vince Lombardi lasted from 1959 to 1967."