A word in a BTS song, Illegal/Dimple. "Those dimples are illegal, so i call you illegirl."

Used to describe (generally female) imagery that's suggestive, but in a PG-13 sense rather than an R or above sense.

a girl so cute that she is deemed illegal.

a term to descirbe a girl you find attractive but is either under age, or currently unavailable, so would be wrong to try and make something happen with this girl