thick-pated

It seemed strange that any one should ever trust that unscrupulous, callous, thick-pated diplomatic-secret-service machine which is always ready to expose a too confiding and admiring friend to danger or disgrace in order to serve its imperious necessities.

Fighting For Peace Henry Van Dyke 1892

Now, watch me, ye thick-pated rookies, and, as I describe it, bit by bit, I'll come to the position of the soldier. "

Uncle Sam's Boys in the Ranks or, Two Recruits in the United States Army 1895