The 100th anniversary of a significant event or the period of 100 years.
From Latin 'centenarius' (of or pertaining to a hundred), derived from 'centum' (hundred). English adopted the term in the 1700s to mark the celebration of 100-year milestones.
Historians have discovered that humans unconsciously mark time in round centuries—we remember 1900 and 2000 far more vividly than 1899 or 2001, suggesting our brains have an inbuilt calendar module that celebrates the digits rolling over.
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