Anhydrous acetone is an acetone with no water in it. Acetone, which is also known as propanone, is a ketone in liquid form and highly flammable and volatile, according to Chemical.net.
Acetone can be made dry by adding anhydrous magnesium sulfate to it. The sulfate should be hot because it can easily absorb water from the atmosphere when cold. Presence of water in solvents like acetone may cause unwanted reaction or formation of unwanted products during a reaction. Besides being a synthetic reagent, acetone is also used as an organic solvent. WonderHowTo.com highlights that this solvent can also be used in removing nail polish. Sigmaaldrich.com, which retails dry solvents, shows the physical properties and the price of acetone.