noun
body surface
Technical term used in anatomy, medicine, and biology to refer to the external surface of the body.
体表面積は、薬の投与量を決めるのに使われる。
Body surface area is used to determine drug dosage.
皮膚 means 'skin' and refers specifically to the organ, while 体表面 is the abstract surface area of the body.
Compound of 体 (body) and 表面 (surface).