Vanadous acid is a chemical compound that consists of vanadium, oxygen, and hydrogen. It is also known as orthovanadous acid or vanadium(II) oxide hydrate. There are several synonyms for vanadous acid including dihydroxidovanadium, vanadium dihydroxide, and vanadium(II) hydroxide. Additionally, it is sometimes referred to as vanadium oxide (IV) hydrate or vanadium dihydroxide hydrate. The use of these synonyms is important in the field of chemistry as it helps to avoid confusion or mix-ups when referring to the same compound. Despite the different names, they all refer to the same chemical formula of V(OH)2.