Webster's 1913 Dictionary
PIG-HEADED
PIG-HEADED Pig "-head `ed, a.
Defn: Having a head like a pig; hence, figuratively: stupidity obstinate; perverse; stubborn. B. Jonson. -- Pig "-head `ed *ness, n.
Oxford Dictionary
pig-headed
pig-headed ▶adjective stupidly obstinate. DERIVATIVES pig-headedly adverb, pig-headedness noun
Oxford Thesaurus
pig-headed
pig-headed adjective obstinate, stubborn, stubborn as a mule, mulish, bull-headed, obdurate, headstrong, self-willed, wilful, perverse, contrary, recalcitrant, refractory, stiff-necked; tenacious, dogged, single-minded, inflexible, uncompromising, adamant, intractable, intransigent, unyielding, unmalleable, unpersuadable.