Its source is a Greek expression meaning "Secure."
This girl's name is used in Greek.
In Greek mythology, Atalante was a huntress of legendary power, and one of the Argonauts. She was especially known for her swiftness, and she challenged the heroes around her to race -- if the man won, he could marry her. If she won, she could dispose of the loser's life.
Many attempted to defeat her, only to fail and suffer death at her hand. Eventually a Greek warrior (either Meilanion or Hippomenes, depending on the version of the tale) was able to defeat her by a stratagem. As he ran, he dropped in front of her three golden apples he obtained from the goddess Aphrodite. The huntress paused to pick them up, he finished ahead of her and she was his.