Millie can be considered a diminutive of Mildred or Millicent. The name Mildred comes from the Old English name Mildþryð, meaning "gentle strength" (from the elements milde - "gentle" and þryð - "strength"). Millicent is a Germanic name derived from the name Amalasuintha, meaning "hard worker" (from the elements amal - "work, labour" and swinth - "strong"). As a stand-alone name, Millie peaked in popularity in the early 2000s.