The term "airbrain" is often used to describe someone who is foolish or lacks intelligence. Some synonyms for this word include "dingbat," "nitwit," "dope," "idiot," "simpleton," and "moron." Other similar terms include "fool," "dolt," "halfwit," and "imbecile." These words can be used interchangeably to express the same sentiment as "airbrain," though some may be more or less offensive depending on the context. When choosing an appropriate synonym, it's important to consider the potential impact on the person or group being described, as well as the desired level of emphasis or insult.