Green’s Dictionary of Slang

(US) a fool.

1915		Wash. Times (DC) 19 Mar. 14/2: Hey! Ironhead, tryin’ t’ win t’ game with a field goal?
1922		T. Thursday ‘Ten Dollars – No Sense’ in Top-Notch 15 Dec. 🌐 I’m getting wisdom, you ironhead — wisdom!
1973		J.R. Coleman Blue-Collar 38: The trouble with you guys is you’re all ironheads. You don’t think .