Milly is an English short form of several longer names: Millicent, from the Germanic amal and swinth, "strong worker", as well as Mildred, Camilla, Amelia and Emilia. The spelling with y is the less common American twin of Millie. Milly has held a very steady place between number 1657 and number 2200 since 2014 and ranks 1790 among girls' names in 2025.