What is millie short for?

Millie is a diminutive form of the name Mildred, Millicent, or Camilla. The name Millie is of English origin and means "gentle strength" or "brave strength." Millie is a popular name for girls in English-speaking countries and has been in use since the 19th century. It is often used as a standalone name rather than as a nickname for longer names. Millie is a sweet and charming name that conveys qualities of kindness, bravery, and resilience.