Laundry is a noun that refers to the act of washing

Washing

Washing is one way of cleaning, namely with water and often some kind of soap or detergent. Washing is an essential part of good hygiene and health....

 clothing

Clothing

Clothing refers to any covering for the human body that is worn. The wearing of clothing is exclusively a human characteristic and is a feature of nearly all human societies...

 and linen

Linen

Linen is a textile made from the fibers of the flax plant, Linum usitatissimum. Linen is labor-intensive to manufacture, but when it is made into garments, it is valued for its exceptional coolness and freshness in hot weather....

s, the place where that washing is done, and/or that which needs to be, is being, or has been laundered. Laundry can be considered a room or area, as in a home or apartment building, reserved for doing the family wash.
Laundry was first done in watercourse

Watercourse

A watercourse is any flowing body of water. These include rivers, streams, anabranches, and so forth.-See also:* physical geography* Environmental flow* Waterway* Hydrology* Wadi-External links:...

s , letting the water carry away the materials which could cause stains

Stains

Stains is a commune in the northern suburbs of Paris, France. It is located from the center of Paris.-Heraldry:-Transport:Stains is served by Pierrefitte – Stains station on Paris RER line D...

 and smells.