From Wiktionary, the free dictionary
From hohl + Kopf.
Hohlkopf m (strong, genitive Hohlkopfes or Hohlkopfs, plural Hohlköpfe, feminine (rare) Hohlköpfin)
- (derogatory) stupid person; airhead
Declension of Hohlkopf [masculine, strong]
- “Hohlkopf” in Digitales Wörterbuch der deutschen Sprache
- “Hohlkopf” in Duden online
- “Hohlkopf” in Uni Leipzig: Wortschatz-Lexikon