Use Retin-A exactly as your doctor has prescribed it for you. Follow all directions on your prescription label. Do not use this medicine in larger or smaller amounts or for longer than recommended. Do not take by mouth. Retin-A is for use only on the skin.
Definition of wall for English Language Learners : a structure of brick, stone, etc., that surrounds an area or separates one area from another : the structure that forms the side of a room or building
On the Facebook, social networking site a wall is a section in your profile where others can write messages to you or leave you gifts, which are icon-like small images. The wall is a public writing space so others who view your profile can see what has been written on your wall.