Airheads is a term used to describe someone who is not very bright or intelligent. There are a plethora of synonyms that can be used to replace this term. One of the most common synonym is the word "dimwit". Other synonyms for airheads include "dumbbell", "blockhead", "numbskull", "slow-witted", "brain-dead", "simpleton", and "ignoramus". Each of these synonyms could be used in the same context as airheads to describe someone who is intellectually challenged. It is important to remember that using derogatory terms to describe someone is never appropriate, regardless of their intellectual capacity.