The ethan- stem means you have two carbons, and the -oic acid ending means that the carbon on the end is part of a carboxylic acid group, -COOH. So ethanoic acid is CH3COOH, which is more commonly known as acetic acid.Anhydrous (water-free) acetic acid is sometimes called glacial acetic acid because it solidifies just below room temperature, at 16.7°C. Acetic acid can be concentrated by dripping the impure compound over a "stalactite" of glacial (frozen) acetic acid. Pure acetic acid crystallizes, while impurities run off in the liquid.
Glacial acetic acid is a trivial name for water-free acetic acid. Usually acetic acid containing usually less than 1 percent of water Glacial acetic acid is anhydrous form of acetic acid in which it exists in dimmer form. It's known as Glacial because on freezing it forms needle shape crystals.