century (100 years)

guinea (British gold coin)

century

to use / to employ / to make use of, to apply / to spend

a Briton, a British person, a person from the United Kingdom

guinea pig

United Kingdom (a country in Europe) / (loosely, chiefly attributive) Synonym of ブリテン (Buriten, “Britain”) / (loosely) Synonym of イングランド (Ingurando, “England”) (region of Great Britain)

restricted to those under 18 years of age, due to serious sexual content

use one thing for many purposes / work someone hard

end of a century / end of an era; fin de siècle / (chiefly fiction) end of the world