What type of acid is phenol commonly known as?

Phenol is commonly known as carbolic acid, which is appropriate due to its historical use as a disinfectant and antiseptic. The term "carbolic acid" is derived from its use in carbolic soap and as a component in coal tar distillation, highlighting its origins in the context of early medicinal chemistry. Phenol has a hydroxyl group (-OH) attached to a benzene ring, which contributes to its properties and applications in various industries, including the production of plastics and resins.

Other acids listed serve different purposes and are distinct in their chemical structure and uses. Hydrochloric acid is a strong acid used in various industrial processes; acetic acid is primarily known for its use in vinegar; and citric acid is commonly found in citrus fruits and is widely used as a food preservative and flavoring agent. These alternatives do not relate to phenol's identity or historical nomenclature as closely as carbolic acid does.