Casimir, of Polish origin, is a masculine given name that has been adopted by various cultures over time. It is derived from the Slavic elements "kasja" meaning 'destroy' and "mir" meaning 'peace', resulting in the name being interpreted as 'destroyer of peace'. However, it is often associated with the idea of 'bringer of peace' due to its patron saint, Saint Casimir, who was known for his piety and devotion. The name has been popular among royalty, with notable bearers including Casimir III the Great, a King of Poland, and Casimir IV Jagiellon, Grand Duke of Lithuania. In French, the name is often spelled Cassimer and in German, it is frequently transliterated as Kasimir or Kazimir. Despite its historical popularity, Casimir remains relatively uncommon today, adding to its uniqueness and distinctiveness.
"Casimier saw a peak in popularity during World War I, with seven births each in 1917 and 1918. However, it seems the name's appeal waned thereafter, with only five births reported in 1919 and none mentioned between 1920 and 1925, except for a single year spike of five births in 1926."