wrongheaded
[adjective]
Synonyms: obstinate, bullheaded, headstrong, mulish, pertinacious, perverse, pigheaded, self-willed, stiff-necked, stubborn, contrary, balky, cross-grained, froward, ornery, restive, wayward

[TahlilGaran] English Synonym Dictionary ▲

wrong‧head‧ed /ˌrɒŋˈhedəd◂, ˌrɒŋˈhedɪd◂ $ ˌrɒːŋ-/ adjective
used to describe an idea, plan, or belief that someone has, that is based on wrong ideas that they are not willing to change
—wrongheadedly adverb
—wrongheadedness noun [uncountable]

[TahlilGaran] Dictionary of Contemporary English ▲