Here's why:
* Origin: Casey is primarily a surname, often of Irish origin, meaning "vigilant" or "watchful."
* Unisex: While the name has been used for both boys and girls, it's become more popular for girls in recent decades.
* Lack of Established Meaning: As a surname adopted as a first name, Casey doesn't carry a traditional, widely recognized meaning like some other names.
Therefore, the meaning of Casey for a girl is often interpreted as "vigilant," "watchful," "bright," or simply "a strong and independent woman." The meaning can also be personalized to reflect the individual's personality or family history.