Noun
(slang) A stupid person.
(slang) A submariner; bubble-head.
(slang) A navy hard hat or salvage diver (inspired by the shape of the old spun-copper diving helmet).
Source: en.wiktionary.orgOnce this was a nation of farmers, builders, inventors, creators, explorers, and thinkers. Now we are a nation of bubblehead academic poseurs, race-guilt hucksters, and keening middle-class "victims" of imaginary wrongs. John Derbyshire