Marylin Monroe wore a size 14. Nowadays she'd be considered "plus size" by Hollywood standards and would never get a job by the casting agents who think "sexy" is a 12 year-old boy and this is the look that female actresses need to aspire to.
I've seen Marilyn's supposed "size 14" dress at the Smithsonian. By today's clothing standards, she'd be a size 6 or 8.