"Dress size" refers to the specific number assigned to a person's clothing, indicating their body measurements and helping them find the right size garment. Full definition
Because dress sizes in the past varied enormously to now, all good vintage stores list the measurements of each outfit clearly. (weheartvintagedirectory.com)
I decided to order a size 2 dress sizes smaller than what I am based on their size chart but it fits me already. (tidebuy.com)
The general rule of thumb is to jump up two dress sizes for pregnant women. (theeverygirl.com)