You likely have one of these at home, a solvent made with some blends of lubricants. It was developed by Rocket Chemical Company back in 1953 to prevent corrosion by displacing water.
Naturally, WD stands for “water displacement”. However, believe it or not, 40 means the 40th attempt … yes the company succeeded on the 40th try, and then used it as part of the product name.
How many times have you tried, before you developed the right products ? 4, 40, 400 ?