The term "anvil cloud" refers to a type of cumulonimbus cloud that resembles an anvil in shape. This cloud formation is also known as a thunderhead, thunderstorm cloud, or a cumulonimbus incus, due to its distinctive flattened top. Another synonym for anvil cloud is a cauliflower cloud, which describes the fluffy appearance of the cloud. A pileus cloud is a cloud that forms on top of an anvil cloud due to the rapid upward motion of air. A mammatus cloud is a lumpy and pouch-like cloud formation that often develops underneath the anvil part of a thunderstorm cloud. All of these synonyms describe different aspects of the anvil cloud, making it easier for people to communicate about this unique weather formation.