The measurements refer to body size, not garment dimensions.
Regular fit: A fit that is not too loose or too baggy. It contours the natural shape of the body for mobility.
Loose fit: A more generous cut. It drapes loosely on the body for maximum comfort.
Oversized fit: A large fit of considerable size and volume.
HOW TO MEASURE
Bust: measure at underarm around the chest, at fullest part of the chest.
Waist: measure around the smallest part of your waist.
Hip: standing straight with your feet together, measure around the fullest part of your hips.
Thigh: While standing, measure your thigh by wrapping the tape around one leg at the midpoint of the thigh, from front to back going in between your legs.
Bicep: With your arm hanging at your side and relaxed, wrap the tape measure around the largest part of your arm, near your armpit.