1. rude. Also: ЧУГУННЫЕ МОЗГИ coll, rude ( usu. appos, vocative, or subj-compl with copula (subj: human) a very stupid, slow-witted person
lamebrain
numskull
bonehead
blockhead
dolt.
2. - (у кого)
VP subj. with быть« or obj) s.o. has a feeling of sluggishness, heaviness in the head: голова (у X-a) была чугунная - X's head was (felt) heavy
X's head was (felt) like lead
X's head felt as if (like) it weighed a ton
ходить (лежать и т. п.) с чугунной головой = (walk (lie etc) around) with a leaden head.
Большой русско-английский фразеологический словарь. — М.: ACT-ПРЕСС КНИГА. С.И. Лубенская. 2004.