Definition of squarehead in US English:

squarehead

noun

North American
informal
  • 1A stupid or inept person.

    idiot, ass, halfwit, nincompoop, blockhead, buffoon, dunce, dolt, ignoramus, cretin, imbecile, dullard, moron, simpleton, clod
    View synonyms
  • 2offensive A person of German, Dutch, or Scandinavian, especially Swedish, origin.

Pronunciation

squarehead

/ˈskwerˌhed/