What is seen as immodest varies by culture, so be mindful of different standards. That skirt might be viewed as immodest in a conservative country.
Pro Tip 2/3
Formality Level
'Immodest' often suggests disapproval and is not typically used in casual conversation. The article discussed the actress's immodest attire with disapproval.
Pro Tip 3/3
Connotation
'Immodest' can imply excessive display of one's body, possibly suggesting sexual availability. Her immodest dancing raised eyebrows amongst the older guests.