Double-dome is a slang term used to describe an intellectual or someone who is highly educated. It is often used in a derogatory manner to suggest that the person is overly academic or pretentious. Synonyms for this term may include "brainiac," "nerd," "egghead," or "genius." While these terms carry similar connotations, they may be perceived differently depending on the context. Some alternative phrases to consider may include "knowledgeable," "expert," "intellectual powerhouse," or "scholar." These words focus more on the person's expertise and abilities rather than solely on their level of education or intellect.