Why hydrochloric acid is called a muriatic acid?

Answer 1

It's just another way to say it. It also applies to a more dilute form of the acid, used for home cleaning.

Answer 2

Hydrochloric acid is commonly referred to as muriatic acid because historically it was produced from brine (saltwater) that was distilled in pots made from clay, also known as "muria," hence the term "muriatic." This name has persisted in common usage even though hydrochloric acid is now typically produced through different chemical processes.

Answer 3

'Muriatic Acid' is its historical alchemical name.

Hydrochloric acid is the modern name.