It gained popularity in 2006 as the title of the hit song by The Black Eyed Peas, featuring Fergie. The song celebrates and embraces female empowerment and confidence, making "fergalicious" a playful and catchy way to describe a confident and attractive woman.
While it's often used to describe someone's physical appearance, "fergalicious" can also refer to someone's personality or aura. It's essentially a fun and playful way to say someone is "hot" or "cool".